Halacha

הלכה א
אֵין תּוֹרְמִין אֶלָּא מִן הַיָּפֶה שֶׁנֶּאֱמַר (במדבר יח ל) (במדבר יח לב) "בַּהֲרִימְכֶם אֶת חֶלְבּוֹ מִמֶּנּוּ". וְאִם אֵין שָׁם כֹּהֵן תּוֹרֵם מִן הַמִּתְקַיֵּם אַף עַל פִּי שֶׁיֵּשׁ שָׁם יָפֶה שֶׁאֵינוֹ מִתְקַיֵּם. כֵּיצַד. תּוֹרֵם תְּאֵנִים עַל הַגְּרוֹגָרוֹת. וּבְמָקוֹם שֶׁאֵין שָׁם כֹּהֵן תּוֹרֵם גְּרוֹגָרוֹת עַל הַתְּאֵנִים. וְאִם רָגִיל לַעֲשׂוֹת תְּאֵנִים גְּרוֹגָרוֹת תּוֹרֵם מִן הַתְּאֵנִים עַל הַגְּרוֹגָרוֹת אֲפִלּוּ בְּמָקוֹם שֶׁאֵין שָׁם כֹּהֵן. אֲבָל בְּמָקוֹם שֶׁיֵּשׁ בּוֹ כֹּהֵן אֵין תּוֹרְמִין מִן הַגְּרוֹגָרוֹת עַל הַתְּאֵנִים אֲפִלּוּ לְמָקוֹם שֶׁדַּרְכָּן לַעֲשׂוֹת תְּאֵנִים גְּרוֹגָרוֹת:
כסף משנה
1.
We should separate terumah only from the most choice [produce], as [implied by Numbers 18:30]: "When you separate its most choice portion from it."1Chelbo, translated as "most choice portion," literally means "fat."
When quoting this law, the Shulchan Aruch (Yoreh De'ah 331:52) states that in the present age, when terumah will be destroyed regardless, there is no need to separate the most choice portions as terumah.
See also the Ramban's Hosafot to Sefer HaMitzvot (Negative Mitzvah 7) which considers the adjuration against separating lower quality produce as terumah as one of the Torah's 613 prohibitions.
If, however, there is no priest accessible,2And thus the terumah will not be able to be given to the priest immediately. one should separate terumah from produce that will last3I.e., since there is no priest immediately available, it is preferable to separate produce that will not spoil, so that ultimately, it can be given to a priest. even though there is more choice produce but it will not last.
What is implied? A person should separate fresh figs as terumah for dried figs.4For fresh figs are tastier and considered as a higher grade produce. In a place where there are no priests, he should separate dried figs for fresh figs.5I.e., since there is no priest immediately available, it is preferable to separate produce that will not spoil, so that ultimately, it can be given to a priest. If he is accustomed to dry fresh figs, he may separate fresh figs as terumah for dried figs even in a place where there is no priest.6For he will dry the figs himself and prevent them from spoiling before they are given to the priest. In a place where there is a priest, by contrast, dried figs are never separated as terumah for fresh figs, even in a place where it is customary to dry fresh figs.

הלכה ב
תּוֹרְמִין בָּצָל שָׁלֵם אַף עַל פִּי שֶׁהוּא קָטָן. אֲבָל לֹא חֲצִי בָּצָל אַף עַל פִּי שֶׁהוּא גָּדוֹל. בְּכָל מָקוֹם אֵין תּוֹרְמִין מִמִּין עַל שֶׁאֵינוֹ מִינוֹ שֶׁנֶּאֱמַר (במדבר יח כז) "כַּדָּגָן מִן הַגֹּרֶן וְכַמְלֵאָה מִן הַיֶּקֶב". וְאִם תָּרַם אֵין תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
2.
One may separate an entire onion as terumah even if it is small,7A whole onion is considered more important and choicer than a portion of an onion [the Rambam's Commentary to the Mishnah (Terumot 2:5)]. but not half an onion, even if it is large in all places.8I.e., in places where a priest is present or those where he is not present, for a whole onion will keep longer than a cut one (ibid.). We do not separate one type of produce as terumah for another type of produce, as [implied by Numbers 18:30]: "As grain from the granary and as wine from the vat."9Implied is that the terumah and the produce for which it is being separated must be of the same species. If one made such a separation, it is not considered terumah.

הלכה ג
הַקְּשׁוּת וְהַמְּלָפְפוֹן מִין אֶחָד. כָּל מִין חִטִּים אֶחָד. כָּל מִין תְּאֵנִים וּגְרוֹגָרוֹת וּדְבֵלָה אֶחָד. וְתוֹרֵם מִזֶּה עַל זֶה. וְכָל שֶׁהוּא כִּלְאַיִם בַּחֲבֵרוֹ לֹא יִתְרֹם מִזֶּה עַל זֶה אֲפִלּוּ מִן הַיָּפֶה עַל הָרַע. כֵּיצַד. הָיוּ לוֹ חֲמִשִּׁים סְאָה חִטִּין וַחֲמִשִּׁים סְאָה שְׂעוֹרִים בְּבַיִת אֶחָד וְהִפְרִישׁ עַל הַכּל שְׁנֵי סְאִין חִטִּין אֵינָן תְּרוּמָה. וְכָל שֶׁאֵינוֹ כִּלְאַיִם בַּחֲבֵרוֹ תּוֹרֵם מִן הַיָּפֶה עַל הָרַע אֲבָל לֹא מִן הָרַע עַל הַיָּפֶה. וְאִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה חוּץ מִן הַזּוֹנִין עַל הַחִטִּים מִפְּנֵי שֶׁאֵינָן אֹכֶל אָדָם:
כסף משנה
3.
Zucchini and cucumbers are considered as one species.10They are also considered as one species with regard to the prohibition against kilayim (Hilchot Kilayim 3:3). All of the types of wheat are one species. All of the types of figs,11I.e., light figs and dark figs. dried figs, and blocks of figs are one species. [In the above instances,] one may separate terumah from one type for the other. [By contrast,] all types of produce which are considered as a mixture of species may not be separated as terumah for each other, even when one separates the choicest produce as terumah for produce of lesser quality.
What is implied? A person has 50 se'ah of wheat and 50 se'ah of barley in one building. If he separates two se'ah of wheat [as terumah] for the entire amount, his separation is not effective.12Because wheat and barley are different species. Moreover, it is considered as if terumah has not been separated even from the wheat alone. The rationale is that separating terumah is considered equivalent to taking a vow and if a portion of a vow has been nullified, the entire vow is nullified. When types of produce are not considered as a mixture of species, one may separate the better type as terumah for the lesser type, but not the lesser type as terumah for the better type. If one did separate [the lesser type of produce as terumah for the better type, after the fact,] the separation is effective with one exception. Zunin13A coarse species of wild wheat.may not be separated as terumah for wheat, because it is not used as food for humans.

הלכה ד
אֵין תּוֹרְמִין מִדָּבָר שֶׁנִּגְמְרָה מְלַאכְתּוֹ עַל דָּבָר שֶׁלֹּא נִגְמְרָה מְלַאכְתּוֹ. וְלֹא מִדָּבָר שֶׁלֹּא נִגְמְרָה מְלַאכְתּוֹ עַל דָּבָר שֶׁלֹּא נִגְמְרָה מְלַאכְתּוֹ. וְלֹא מִדָּבָר שֶׁלֹּא נִגְמְרָה מְלַאכְתּוֹ עַל דָּבָר שֶׁנִּגְמְרָה מְלַאכְתּוֹ. שֶׁנֶּאֱמַר (במדבר יח כז) "כַּדָּגָן מִן הַגֹּרֶן וְכַמְלֵאָה מִן הַיֶּקֶב" מִן הַגָּמוּר עַל הַגָּמוּר. וְאִם תָּרְמוּ תְּרוּמָתָן תְּרוּמָה:
כסף משנה
4.
We do not separate terumah from produce for which all the work [in preparing it] was completed14At which point the obligation to separate terumah and the tithes falls upon it (see Chapter 1, Halachah 11, and notes). for produce for which the work [in preparing it] is incomplete, from produce for which the work [in preparing it] is incomplete for [other] produce for which the work [in preparing it] is incomplete, nor from produce for which the work [in preparing it] is incomplete for produce for which all the work [in preparing it] was completed.15The commentaries note that the order of the clauses employed by the Rambam deviates slightly from the order of his source, Terumot 1:10. [This is also derived from the above prooftext:] "As grain from the granary and as wine from the vat."16The Rambam and previous Rabbinic sources cite several prooftexts for this law. Nevertheless, the Siftei Cohen 331:80 maintains that the law is a Rabbinic decree and the prooftexts are merely asmachteot, allusions cited for support. For that reason, after the fact, the separation is effective. [Implied is that terumah should be separated from produce] for which [all work] was completed for similar produce. If, however, one separated terumah [in any of the above instances], the separation is effective [after the fact].17See Halachot 18-20 for more particulars concerning this issue.

הלכה ה
מֵאֵימָתַי תּוֹרְמִין אֶת הַגֹּרֶן מִשֶּׁיִּבְרֹר. בָּרַר מִקְצָת תּוֹרְמִין מִן הַבָּרוּר עַל שֶׁאֵינוֹ בָּרוּר. הַמַּכְנִיס שִׁבֳּלִים לְתוֹךְ בֵּיתוֹ לַעֲשׂוֹתָן מְלִילוֹת הֲרֵי זֶה תּוֹרֵם מִן שִׁבֳּלִים:
כסף משנה
5.
When should terumah be separated from a granary? When the kernels are separated.18When the grain has been threshed and winnowed and then the kernels separated from the chaff. Different commentaries suggest a slight change in the Rambam's wording which would cause the produce to be considered as complete at an earlier stage. If a person separated part [of the grain], he may designate the kernels he separated as terumah for the produce that was not separated. When one brings stalks of grain into his home to eat husked grain, he should separate terumah while the grain is in the stalks.19Because they will not be processed any further.

הלכה ו
מֵאֵימָתַי תּוֹרְמִין אֶת הַגַּת מִשֶּׁיְּהַלְּכוּ בָּהּ שְׁתִי וָעֵרֶב. מֵאֵימָתַי תּוֹרְמִין אֶת הַזֵּיתִים מִשֶּׁיִּטְעֲנוּ:
כסף משנה
6.
When should terumah be separated from a vat? When [the treaders] have walked horizontally and vertically over the grapes.20For then, the wine has been separated from the grapes.
When should one separate terumah from olives? When [the beam of the press] is placed upon them.21For then, the oil has been separated from the olives.

הלכה ז
אֵין תּוֹרְמִין מִן הַטָּהוֹר עַל הַטָּמֵא וְאִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה. וַהֲלָכָה לְמשֶׁה מִסִּינַי שֶׁעִגּוּל שֶׁל דְּבֵלָה שֶׁנִּטְמָא מִקְצָתוֹ תּוֹרְמִין לְכַתְּחִלָּה מִן הַטָּהוֹר שֶׁבּוֹ עַל הַטָּמֵא שֶׁבּוֹ. וְלֹא הָעִגּוּל בִּלְבַד שֶׁהוּא גּוּף אֶחָד אֶלָּא אֲפִלּוּ אֲגֻדָּה שֶׁל יָרָק אֲפִלּוּ עֲרֵמוֹת שֶׁל חִטִּים שֶׁנִּטְמְאָה מִקְצָתָהּ תּוֹרְמִין מִן הַטָּהוֹר שֶׁבָּהּ עַל הַטָּמֵא שֶׁבָּהּ. אֲבָל אִם הָיוּ שְׁנֵי עִגּוּלִים אוֹ שְׁתֵּי אֲגֻדּוֹת אוֹ שְׁתֵּי עֲרֵמוֹת אַחַת טְמֵאָה וְאַחַת טְהוֹרָה בְּצִדָּהּ לֹא יִתְרֹם מִן הַטָּהוֹר עַל הַטָּמֵא לְכַתְּחִלָּה. וְתוֹרְמִין תְּרוּמַת מַעֲשֵׂר מִן הַטָּהוֹר עַל הַטָּמֵא לְכַתְּחִלָּה שֶׁנֶּאֱמַר (במדבר יח כט) "אֶת מִקְדָּשׁוֹ מִמֶּנּוּ" טֹל מִן הַמְקֻדָּשׁ שֶׁבּוֹ:
כסף משנה
7.
We should not separate terumah from ritually pure produce for produce that is not ritually pure.22The Jerusalem Talmud (Terumot 2:1) derives this concept from the prooftext cited above: "As grain from the granary and as wine from the vat." It is impossible that a vat will be partially pure and partially impure, so, too, terumah and the produce for which it is being separated must be either pure or impure." If, however, one separated terumah [in this manner], the separation is effective [after the fact].
It is a halachah conveyed to Moses at Sinai that when a portion of a cake of dried figs has become impure, we may separate terumah from the pure portion of it for the impure portion of it as an initial preference.23In his Commentary to the Mishnah (Terumot 2:1), the Rambam explains the rationale for this law. Since the cake of figs is made from several discrete elements, it is not considered as a single entity with regard to the laws of ritual impurity. Hence, the fact that one portion has been touched by a source of ritual impurity does not cause another portion to become impure. Nevertheless, since it is one body of produce, terumah can be separated from one portion for the other. This applies not only to a cake of dried figs which appears as one mass, but also to a bundle of vegetables and even a mound of wheat.24In these instances as well, since the whole is made up of discrete entities, the fact that they are connected or somewhat associated is not of consequence (ibid.; see also Hilchot Tuma'at Ochalin 6:14). If a portion of it became impure, one may separate terumah from the pure portion for the impure portion.
If, however, there were two cakes of dried figs, two bundles of vegetables, or two mounds of wheat, one impure and one pure at its side, as an initial preference, one should not separate terumah from the produce that is pure for the produce that is impure.25For the two are not considered as being "in the same place" (min hamukaf). After the fact, however, the separation is acceptable. One may, however, separate terumat ma'aser from produce that is pure for produce that is impure as an initial preference. [This is derived from Numbers 18:29:] "its sacred portion from it." [Implied is that] one should take from the sacred portion in it.26The verse indicates that when one is separating terumat ma'aser, it is possible that there be a "sacred." i.e., pure, portion, and a portion that is not "sacred," i.e., impure, and the pure should be separated for the impure. As stated at the conclusion of ch. 3, the produce separated as terumat ma'aser need not be located together with the produce for which it is being separated.

הלכה ח
אֵין תּוֹרְמִין מִן הַטָּמֵא עַל הַטָּהוֹר וְאִם תָּרַם בְּשׁוֹגֵג תְּרוּמָתוֹ תְּרוּמָה. בְּמֵזִיד לֹא תִּקֵּן אֶת הַשְּׁיָרִים וְזֶה שֶׁהֵרִים תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם. בַּמֶּה דְּבָרִים אֲמוּרִים שֶׁלֹּא יָדַע בַּטֻּמְאָה. אֲבָל אִם יָדַע וְשָׁגַג שֶׁמֻּתָּר לִתְרֹם מִן הַטָּמֵא עַל הַטָּהוֹר הֲרֵי הוּא כְּמֵזִיד. וְכֵן בִּתְרוּמַת מַעֲשֵׂר:
כסף משנה
8.
We may not separate produce that is ritually impure as terumah for produce that is ritually pure.27The Radbaz states that this is a Rabbinic decree instituted so that the priest will not suffer a loss. If one made such a separation inadvertently, the portion separated is terumah.28For according to Scriptural Law, the separation is effective. In his Commentary to the Mishnah (Terumot 2:2), the Rambam explains that this is speaking about a situation where initially, at the time the obligation to separate terumah took effect, the produce separated as terumah was pure. If, however, it became impure before the work associated with its preparation was completed, even if it was inadvertently separated as terumah, the separation is not effective. If one made the separation intentionally, he did not fulfill the obligation for the remainder [of the produce], but [the produce] separated is terumah. He must separate terumah a second time.
When does the above apply? When he did not know of the impurity. If, however, he knew of the impurity, but erred in that he thought it was permitted to separate produce that is ritually impure as terumah for produce that is ritually pure, he is considered as if he acted intentionally.29And he must make another separation. Similar laws apply with regard to terumat ma'aser.

הלכה ט
אֵין תּוֹרְמִין מִן הַמְחֻבָּר עַל הַתָּלוּשׁ וְלֹא מִן הַתָּלוּשׁ עַל הַמְחֻבָּר. כֵּיצַד. הָיוּ לוֹ פֵּרוֹת תְּלוּשִׁין וְאָמַר פֵּרוֹת אֵלּוּ יִהְיוּ תְּרוּמָה עַל פֵּרוֹת אֵלּוּ הַמְחֻבָּרִים אֲפִלּוּ (אָמַר) לִכְשֶׁיִּתָּלְשׁוּ. אוֹ שֶׁהָיוּ לוֹ שְׁתֵּי עֲרוּגוֹת וְאָמַר פֵּרוֹת עֲרוּגָה זוֹ תְּלוּשִׁין יִהְיוּ תְּרוּמָה עַל פֵּרוֹת עֲרוּגָה זוֹ מְחֻבָּרִים. אוֹ שֶׁאָמַר פֵּרוֹת עֲרוּגָה זוֹ מְחֻבָּרִים יִהְיוּ תְּרוּמָה עַל פֵּרוֹת עֲרוּגָה זוֹ תְּלוּשִׁין לֹא אָמַר כְּלוּם. אֲבָל אִם אָמַר פֵּרוֹת עֲרוּגָה זוֹ תְּלוּשִׁין יִהְיוּ תְּרוּמָה עַל פֵּרוֹת עֲרוּגָה זוֹ לִכְשֶׁיִּתָּלְשׁוּ וְנִתְלְשׁוּ הוֹאִיל וּבְיָדוֹ לְתָלְשָׁן אֵינוֹ מְחֻסָּר מַעֲשֶׂה וְלִכְשֶׁיִּתָּלְשׁוּ שְׁנֵיהֶם דְּבָרָיו קַיָּמִין. וְהוּא שֶׁיָּבִיאוּ שְׁתֵּיהֶן שְׁלִישׁ בְּעֵת שֶׁאָמַר:
כסף משנה
9.
We may not separate produce that is still attached to the earth as terumah for produce that has already been detached.30The Sifri derives this from the exegesis of Numbers 18:26: "And you shall separate from it...." Since the produce is still attached to the earth, it is not considered as the same type as the produce which is detached. Nor may produce that has already been detached be separated as terumah for produce that is still attached to the earth.
What is implied? A person had produce that was detached and said: "This produce will be terumah for this produce which is attached to the earth" - and even if he said "...when [the attached produce] is detached,"31To reconcile the apparent contradiction between the Rambam's ruling here and that in the following clause, the commentaries explain that here we are speaking of attached produce that does not belong to the person who wishes to separate terumah. Ordinarily, if a person separated terumah from produce belonging to him for produce that does not belong to him, his separation is valid, as stated in Chapter 4, Halachah 2. In this instance, however, since the attached produce does not belong to him and he has no control of when it will be detached, he does not have the potential to designate his own produce as terumah for it. his words are of no consequence. [This ruling also applies] if he possessed two rows [of produce] and said: "The produce of this row which is detached will be terumah for this row which is attached," or "The produce of this row which is attached will be terumah for this row which is detached."
[Diferent rules apply should] he say: "The produce of this row which is detached will be terumah for this row when it will be detached," if [the produce] is [later] detached - since it is within his potential to detach it32This is his own produce which he is allowed to detach. - when they are both detached, his words are binding, provided both [types of produce] had attained at least a third of their standard size33For until produce reaches this size, there is no obligation to separate terumah, as stated in Chapter 2, Halachah 10. Therefore, even if one separated terumah for it, the separation is not effective. at the time he made his statements.

הלכה י
אֵין תּוֹרְמִין מִן הַלַּח עַל הַיָּבֵשׁ וְלֹא מִן הַיָּבֵשׁ עַל הַלַּח. וְאִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה. כֵּיצַד. לִקֵּט יָרָק הַיּוֹם וְלִקֵּט מִמֶּנּוּ לְמָחָר אֵין תּוֹרְמִין מִזֶּה עַל זֶה אֶלָּא אִם כֵּן דַּרְכּוֹ לְהִשְׁתַּמֵּר שְׁנֵי יָמִים. וְכֵן יָרָק שֶׁדַּרְכּוֹ לְהִשְׁתַּמֵּר שְׁלֹשָׁה יָמִים כְּגוֹן הַמְּלָפְפוֹנוֹת כָּל שֶׁלִּקֵּט בִּשְׁלֹשֶׁת יָמִים מִצְטָרֵף וְתוֹרֵם מִזֶּה עַל זֶה. יָרָק שֶׁדַּרְכּוֹ לְהִשְׁתַּמֵּר יוֹם אֶחָד בִּלְבַד וְלִקֵּט בְּשַׁחֲרִית וְלִקֵּט בָּעֶרֶב תּוֹרֵם מִזֶּה עַל זֶה:
כסף משנה
10.
We may not separate fresh produce as terumah for dried produce, nor dried produce as terumah for fresh produce. If, however, one made such a separation, it is effective.34The Siftei Cohen 331:83 states that this is a Rabbinic decree, enacted as a safeguard so that one will not separate produce from one type over another. Hence, after the fact, the separation is effective.
What is implied? One reaped a type of vegetable one day and then reaped the same [type of vegetable] the following day. One may not separate one as terumah for the other unless this vegetable remains fresh for two days. Similarly, if a vegetable usually remains fresh for three days, e.g., cucumbers, all [of that type of vegetable] that are harvested for three days may be joined together and terumah may be separated from one for the other. When a type of vegetable remains fresh for only one day and one harvested some in the morning and some in the evening, one may separate one as terumah for the other.

הלכה יא
אֵין תּוֹרְמִין מִפֵּרוֹת שָׁנָה זוֹ עַל פֵּרוֹת שָׁנָה שֶׁעָבְרָה. וְלֹא מִפֵּרוֹת שָׁנָה שֶׁעָבְרָה עַל פֵּרוֹת שָׁנָה זוֹ. וְאִם תָּרַם אֵינָהּ תְּרוּמָה שֶׁנֶּאֱמַר (דברים יד כב) "שָׁנָה שָׁנָה". לִקֵּט יָרָק עֶרֶב רֹאשׁ הַשָּׁנָה עַד שֶׁלֹּא בָּאָה הַשֶּׁמֶשׁ וְחָזַר וְלִקֵּט אַחַר שֶׁבָּאָה הַשֶּׁמֶשׁ אֵין תּוֹרְמִין מִזֶּה עַל זֶה שֶׁזֶּה חָדָשׁ וְזֶה יָשָׁן. וְכֵן אִם לִקֵּט אֶתְרוֹג בְּעֶרֶב ט''ו בִּשְׁבָט עַד שֶׁלֹּא בָּא הַשֶּׁמֶשׁ וְחָזַר וְלִקֵּט אֶתְרוֹג אַחֵר מִשֶּׁבָּאָה הַשֶּׁמֶשׁ אֵין תּוֹרְמִין מִזֶּה עַל זֶה מִפְּנֵי שֶׁאֶחָד בְּתִשְׁרֵי רֹאשׁ הַשָּׁנָה לְמַעַשְׂרוֹת תְּבוּאָה וְקִטְנִיּוֹת וִירָקוֹת. וְט''ו בִּשְׁבָט רֹאשׁ הַשָּׁנָה לְמַעַשְׂרוֹת הָאִילָן:
כסף משנה
11.
One may not separate produce from the present year as terumah for produce of the previous year,35To clarify the point under discussion in this halachah: As indicated by the concluding phrase of the halachah, "produce from the previous year" does not necessarily mean produce that is a year old. Instead, every Rosh HaShanah, the year of the agricultural cycle changes with regard to vegetables (Rosh HaShanah 14b). As the Rambam proceeds to explain, a Scriptural decree causes such produce to be considered as a discrete entity, distinct from the same type of produce harvested in the present year. nor may one separate produce from the previous year as terumah for produce of the present year. If one made such a separation, it is not effective,36Even after the fact. as [indicated by Deuteronomy 14:22]: "From year to year."37In its entirety, the verse reads: "Tithe all the crops of your sowing produced by the field, year by year." Implied is an exclusion: that the produce of each year is a separate entity. Although the verse refers to the tithes, the same principles also apply to terumah.
In his Commentary to the Mishnah (Terumot 1:5), the Rambam cites a different prooftext for the derivation of this principle.
Thus if one harvested a vegetable on the day preceding Rosh HaShanah before sunset and harvested another after sunset, one may not separate terumah from one for the other. For one is considered "old" and the other, "new."
Similarly, if one harvested an esrog38In that era, esrogim were eaten as fruit, not only used for the mitzvah on Sukkot. on the day before the fifteenth of Shvat on the evening before sunset and harvested another one after sunset [that day], one may not separate terumah from one for the other.39An esrog is singled out, because unlike other fruit, the time when it is picked - and not the time it reaches the stage of development when we are required to separate the tithes - determines the year of the agricultural cycle we follow. See Hilchot Ma'aser Sheni 1:1-4. [The rationale is that] the first of Tishrei is the Rosh HaShanah for tithing grain, legumes, and vegetables and the fifteenth of Shvat is Rosh HaShanah for tithing [of the produce] of trees.

הלכה יב
אֵין תּוֹרְמִין פֵּרוֹת הָאָרֶץ עַל פֵּרוֹת חוּצָה לָאָרֶץ. וְלֹא מִפֵּרוֹת חוּצָה לָאָרֶץ עַל פֵּרוֹת הָאָרֶץ. [וְלֹא מִפֵּרוֹת הָאָרֶץ עַל פֵּרוֹת סוּרְיָא. וְלֹא מִפֵּרוֹת סוּרְיָא עַל פֵּרוֹת הָאָרֶץ]. וְלֹא מִפֵּרוֹת שֶׁאֵינָן חַיָּבִין בִּתְרוּמָה כְּגוֹן לֶקֶט שִׁכְחָה וּפֵאָה. אוֹ פֵּרוֹת שֶׁנִּתְרְמָה תְּרוּמָתָן עַל פֵּרוֹת שֶׁחַיָּבִין בִּתְרוּמָה. וְלֹא מִפֵּרוֹת שֶׁחַיָּבִין בִּתְרוּמָה עַל פֵּרוֹת הַפְּטוּרִין. וְאִם תָּרַם אֵינָהּ תְּרוּמָה:
כסף משנה
12.
We may not separate produce from Eretz [Yisrael] as terumah for produce of the Diaspora, nor may produce of the Diaspora be separated for produce from Eretz Yisrael,40In his Commentary to the Mishnah (Terumot 1:5), the Rambam explains that this concept is derived from Leviticus 27:30: "All the tithes of the land from the plantings of the land." Implied is that both the tithes and the produce must be from "the land," from Eretz Yisrael. Although the verse speaks of the tithes, the principle derived is also applied to terumah. nor may produce of Eretz Yisrael be separated for produce from Syria, and nor may produce of Syria be separated for produce from Eretz Yisrael.41For according to Scriptural Law, Syria is also part of the Diaspora.
Similarly, [we may not separate terumah] from produce for which terumah need not be separated, e.g., leket, shichachah, and pe'ah42See Chapter 2, Halachah 9. or from produce from which terumah was already separated for produce for which terumah must be separated. Nor may we separate terumah from produce for which terumah must be separated for produce for which there is no obligation.43In this instance, the fundamental point the Rambam is emphasizing is the following clause: that even if the terumah was separated, the separation is not of consequence. [Even] if the terumah was separated, the separation is not of consequence.

הלכה יג
הַמַּפְרִישׁ תְּרוּמָה מִמַּעֲשֵׂר רִאשׁוֹן שֶׁלֹּא נִטְּלָה תְּרוּמָתוֹ. אוֹ מִמַּעֲשֵׂר שֵׁנִי וְהֶקְדֵּשׁ שֶׁלֹּא נִפְדּוּ עַל פֵּרוֹת אֲחֵרוֹת אֵין תְּרוּמָתָן תְּרוּמָה:
כסף משנה
13.
When a person separates terumah [for other produce] from produce that was designated as the first tithe, but from which its terumah44I.e., terumah ma'aser, the terumah that must be separated from the tithes. had not been separated45In his Commentary to the Mishnah (Terumot 1:5, Rav Kapach's edition), the Rambam explains that this is referring to a situation in which a Levite took produce that he had been given as tithes by an Israelite, but from which he had not separated terumat ma'aser and desired to use it to separate terumah for produce from his own field from which he is obligated to separate terumah. This is unacceptable, because there is no longer any obligation to separate terumah from the produce given as tithes, even though there is an obligation to separate terumat ma'aser from it.
This explanation is somewhat unique. Most commentaries interpret the mishnah as referring to a situation where the person tithed his crop, but did not separate terumah from it. Nor did he separate terumat ma'aser. Afterwards, he desired to separate terumah for other produce from the tithes. The Rambam's interpretation avoids several difficulties that arise according to the other approach.
or from produce which was designated as the second tithe46Produce separated as the second tithe must be eaten in Jerusalem in a state of ritual purity. It is not considered as the person's private property. or that had been consecrated,47Since it is consecrated, there is no obligation to separate terumah or the tithes from it. but which had not been redeemed, the separation is not effective.48In all these instances, the produce that is being separated is holy and is not the owner's individual property. (For even the tithes which the Levites own have a dimension of holiness to them, because of the terumat ma'aser that has not been separated.) The Ra'avad raises objections to the Rambam's ruling. The Radbaz and the Kessef Mishneh respond to them. If, however, they would have followed the Rambam's explanation in his Commentary to the Mishnah as explained above, the difficulties would not arise.

הלכה יד
אֵין תּוֹרְמִין מִדָּבָר שֶׁהוּא חַיָּב מִן הַתּוֹרָה עַל דָּבָר שֶׁהוּא חַיָּב מִדִּבְרֵיהֶן וְלֹא מִן הַמְחֻיָּב מִדִּבְרֵיהֶן עַל הַחַיָּב מִן הַתּוֹרָה. וְאִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם:
כסף משנה
14.
We may not separate terumah from produce for which we are required to separate terumah according to Scriptural Law for produce for which we are required to separate terumah [only] according to Rabbinic Law,49According to Scriptural Law, there is no obligation to separate terumah from this produce. Hence, it is as if one is separating terumah from produce obligated in terumah for produce for which there is no obligation. The Kessef Mishneh explains that this general principle is derived from the law quoted in the following halachah. nor from produce for which we are required to separate terumah [only] according to Rabbinic Law for produce for which we are required to separate terumah according to Scriptural Law.50For this is as if one is separating terumah from produce for which there is no obligation to separate terumah, for produce for which such an obligation exists. If one separated terumah [in the above instance], the produce separated is considered as terumah,51This is a Rabbinic stringency. According to Scriptural Law, the separation is of no consequence at all. but he must separate terumah again [for the obligation incumbent on this produce to be fulfilled].52According to the Radbaz and the Kessef Mishneh, this applies only to the second clause. The laws regarding the situation described in the first clause are explained in Halachah 16.
In the situation described in the second clause, the priest is allowed to partake of the produce, for although according to Scriptural Law, the separation is insignificant, there is no difficulty in having the priest partake of the produce for there is no obligation incumbent upon it.

הלכה טו
עָצִיץ נָקוּב הֲרֵי הוּא כְּאֶרֶץ. וְכַמָּה יְהֵא בַּנֶּקֶב כְּדֵי שֹׁרֶשׁ קָטָן וְהוּא פָּחוֹת מִכְּזַיִת. זָרַע תְּבוּאָה בְּעָצִיץ שֶׁאֵינוֹ נָקוּב וְהֵבִיאָה שְׁלִישׁ וְאַחַר כָּךְ נִקְּבוֹ וְנִגְמְרָה הַתְּבוּאָה וְהוּא נָקוּב הֲרֵי הוּא כַּצּוֹמֵחַ בְּשֶׁאֵינוֹ נָקוּב עַד שֶׁיִּקְּבֶנּוּ קֹדֶם שֶׁיָּבִיא שְׁלִישׁ:
כסף משנה
15.
A flowerpot with a hole is considered as [connected] to the earth.53Because the nurture from the power of growth in the earth is drawn to the earth in the flowerpot through the hole. This concept is relevant not only in this particular context, but in many others. How large must the hole be [for this law to apply]? Large enough for a small root to pass through it.54For then it can be considered to have derived nurture from the earth through its root. Hence, we are obligated to separate terumah from produce which grows within such a flowerpot according to Scriptural Law [the Rambam's Commentary to the Mishnah (Demai 5:10)]. This is smaller than an olive.
[The following rules apply when a person] planted grain in a flowerpot that did not have a hole and it reached a third of its maturity.55If produce grows in a flowerpot without a hole, there is no obligation to separate terumah from it according to Scriptural Law (ibid.). Here a question arises, because the flowerpot was perforated afterwards. The Rambam clarifies that as long as the produce reaches a third of its growth, the point at which we are obligated to separate terumah, under conditions in which we are not obligated to separate terumah, an obligation is not incurred even though afterwards, those conditions change. See Halachah 9; see also Chapter 1, Halachot 11-13. Afterwards, he perforated [the flowerpot]56And thus enabled the produce to derive nurture from the earth. and the grain completed [its growth] while [the flowerpot] was perforated. It is, [nevertheless,] considered as if it grew in [a flowerpot] without a hole. [This ruling changes] only when [the flowerpot] was perforated before [the grain] reached a third of its maturity.

הלכה טז
הַתּוֹרֵם מִפֵּרוֹת הַגְּדֵלִין בְּאֶרֶץ עַל הַגְּדֵלִין בְּעָצִיץ נָקוּב אוֹ מִפֵּרוֹת עָצִיץ נָקוּב עַל הַגְּדֵלִין בָּאָרֶץ תְּרוּמָתוֹ תְּרוּמָה. תָּרַם מִשֶּׁאֵינוֹ נָקוּב עַל הַנָּקוּב תְּרוּמָתוֹ תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם. תָּרַם מִן הַנָּקוּב עַל שֶׁאֵינוֹ נָקוּב תְּרוּמָתוֹ תְּרוּמָה וְלֹא תֵּאָכֵל עַד שֶׁיּוֹצִיא עָלֶיהָ תְּרוּמָה וּמַעַשְׂרוֹת מִמָּקוֹם אַחֵר:
כסף משנה
16.
When a person separates terumah from produce which grows in the earth for produce that grows in a perforated flowerpot or from produce which grows in a perforated flowerpot for produce which grows in the earth, the separation is effective.57For in both instances, we are obligated to separate terumah from both sets of produce according to Scriptural Law.
If he separates terumah from [produce growing] in a [flowerpot] that was not perforated for [produce growing] in a perforated [flowerpot], the produce separated is considered as terumah,58This is a Rabbinic decree, as stated in Halachah 14 and notes. but he must separate terumah again.59In order to fulfill the obligation of terumah as stated in Halachah 14.
If he separates terumah from [produce growing] in a perforated [flowerpot] for [produce growing] in a [flowerpot] that was not perforated, the produce separated is considered as terumah. [Nevertheless, the priest to whom it was given] should not partake of it until [the owner] separates terumah and tithes for [the portion separated] from other produce.60The setting aside of the produce as terumah is not effective according to Scriptural Law. Hence, according to Scriptural Law, not only is this produce not terumah, it remains tevel, produce from which terumah and the tithes were not separated. Although our Sages ruled stringently and determined that it must be considered as terumah, they did not change its status as tevel. Hence, for the priest to partake of it, it is necessary that he separate terumah and tithes for it from other produce [see the Rambam's Commentary to the Mishnah (Demai 5:10)].
The terumah and the tithes for this produce must be separated from other produce, lest one think that what remains is ordinary produce and can be eaten be a person other than a priest (Tosafot, Yevamot 89b).

הלכה יז
הַתּוֹרֵם מִן הַדְּמַאי עַל הַדְּמַאי וּמִן הַדְּמַאי עַל הַוַּדַּאי תְּרוּמָתוֹ תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם מִכָּל אֶחָד וְאֶחָד בִּפְנֵי עַצְמוֹ. תָּרַם מִן הַוַּדַּאי עַל הַדְּמַאי תְּרוּמָתוֹ תְּרוּמָה וְלֹא תֵּאָכֵל עַד שֶׁיּוֹצִיא עָלֶיהָ תְּרוּמָה וּמַעַשְׂרוֹת:
כסף משנה
17.
When a person separates terumat [ma'aser] from produce that is demai61The term demai refers to produce concerning which we are uncertain whether the tithes were separated from it or not. According to Rabbinic Law, we are required to separate terumat ma'aser, terumah which the Levites are required to separate from the tithes from such produce (see Hilchot Ma'aserot, Chapter 9). for other produce that is demai or from produce that is demai for produce from which we are certain that the tithes were not separated, the produce separated is considered as terumat [ma'aser].62By Rabbinic decree. According to Scriptural Law, the produce separated is not terumat ma'aser, because it is possible that previously tithes and terumat ma'aser had been separated from the produce that was demai. Were that to be the case, one would be separating terumat ma'aser from produce for which one is obligated to make a separation from produce for which no such obligation exists. See the Rambam's Commentary to the Mishnah (loc. cit.). [Nevertheless,] he should separate terumah again for each type of produce individually.63Since it is possible that the separation of the terumat ma'aser is not effective, the owner must make a second separation.
In this instance, the priest is allowed to partake of the produce given him. The rationale is that in the second instance, when one separates terumat ma'aser from produce that is demai for produce from which we are certain that the tithes were not separated, the priest is certainly allowed to partake of the produce given him. If terumat ma'aser had not been separated from such produce previously, it is being made at present. And if it had been made previously, according to Scriptural Law, the produce to be given the priest is ordinary produce that may be consumed.
If the separation was made from produce that is demai for other produce that is demai, there is a difficulty, for it is possible that a separation had previously been made for the produce for which the terumat ma'aser is being separated, but not from the produce from which the separation is being made at present. Since such a separation is invalid according to Scriptural Law, in such an instance, the priest is being given produce from which tithes and terumat ma'aser have not been separated. Nevertheless, since the majority of the people do in fact separate tithes and the prohibition of demai is just a stringency, in this instance, our Sages were lenient (Rabbi Akiva Eiger).

When he separates terumah from produce from which we are certain that the tithes were not separated for produce that is demai, the produce separated is considered as terumat [ma'aser].64This is a Rabbinic stringency as mentioned above. [Nevertheless, the priest to whom it was given] should not partake of it until [the owner] separates terumah and tithes for [the portion separated].65For as in the previous halachah, if the original separation of terumat ma'aser is not effective - as would be the case if a separation had been made from the produce classified as demai - there is an obligation to separate terumat ma'aser from the produce being separated as terumat ma'aser. Hence, until that separation is made, the priest is forbidden to partake of the produce given him.
There is, however, a difference between this halachah and the previous one. In the previous instance, the separation had to be made from other produce, while in this instance, the separation can be made from the produce given to the priest. In the previous instance, care had to be taken because of the impression that might be created, i.e., an onlooker might not realize that there is a Rabbinic obligation to separate terumot and tithes from produce growing in a flowerpot that is not perforated. No such difficulty exists in this instance, because the obligations incumbent on demai are well known. See the gloss of Ra'avad to Hilchot Ma'aser 13:19.

הלכה יח
אֵין תּוֹרְמִין שִׁבֳּלִים עַל הַחִטִּים. וְזֵיתִים עַל שֶׁמֶן. וַעֲנָבִים עַל יַיִן. וְאִם תָּרַם אֵינָהּ תְּרוּמָה גְּזֵרָה שֶׁמָּא יַטְרִיחַ הַכֹּהֵן לִדְרֹךְ וְלִכְתּשׁ. אֲבָל תּוֹרְמִין שֶׁמֶן עַל הַזֵּיתִים הַנִּכְבָּשִׁין וְיַיִן עַל עֲנָבִים לַעֲשׂוֹתָן צִמּוּקִין. לְמָה זֶה דּוֹמֶה לְתוֹרֵם מִשְּׁנֵי מִינִין שֶׁאֵינָן כִּלְאַיִם זֶה בָּזֶה מִן הַיָּפֶה עַל הָרַע. וְכֵן תּוֹרְמִין מִזֵּיתֵי שֶׁמֶן עַל זֵיתֵי כֶּבֶשׁ. אֲבָל לֹא מִזֵּיתֵי כֶּבֶשׁ עַל זֵיתֵי שֶׁמֶן. מִיַּיִן שֶׁאֵינוֹ מְבֻשָּׁל עַל הַמְבֻשָּׁל. אֲבָל לֹא מִן הַמְבֻשָּׁל עַל שֶׁאֵינוֹ מְבֻשָּׁל. מִן הַצָּלוּל עַל שֶׁאֵינוֹ צָלוּל. אֲבָל לֹא מִשֶּׁאֵינוֹ צָלוּל עַל הַצָּלוּל. מִתְּאֵנִים עַל גְּרוֹגָרוֹת בְּמִנְיָן. מִגְּרוֹגָרוֹת עַל הַתְּאֵנִים בְּמִדָּה. אֲבָל לֹא תְּאֵנִים עַל גְּרוֹגָרוֹת בְּמִדָּה. וְלֹא גְּרוֹגָרוֹת עַל הַתְּאֵנִים בְּמִנְיָן. כְּדֵי שֶׁיִּתְרֹם לְעוֹלָם בְּעֵין יָפָה. וְתוֹרְמִין חִטִּים עַל הַפַּת. אֲבָל לֹא מִן הַפַּת עַל הַחִטִּים לְפִי חֶשְׁבּוֹן. וּבְכָל אֵלּוּ אִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
18.
We may not separate stalks of grain as terumah for kernels of grain, olives [as terumah] for oil, or grapes [as terumah] for wine.66This applies even if one separates a measure of produce sufficient to produce the said quantity of wheat, wine, or oil. If one made such a separation, it is not effective.67The Radbaz states that, after the fact, if a priest agrees to accept such produce, the separation is acceptable, for there are times when one will consider that preferable. This is a decree [enacted] lest one cause the priest to undertake the difficulty of treading [on the grapes] or pressing [the olives].
One may, however, separate oil as terumah for olives that are being pickled68But have not been squeezed yet. or wine as terumah for grapes that are being dried as raisins. What does this resemble? To separating terumah from two species that are not considered kilayim, separating from the good for the bad.69This is permissible as stated in Halachah 3.
Similarly, one may separate terumah from olives from which oil will be squeezed70In his Commentary to the Mishnah (Terumot 2:6), the Rambam explains that the Hebrew terms refers to olives that contain much oil and their oil is of high quality. for olives that will be pickled,71I.e., these olives have little oil. Hence, they are set aside to be used for pickling. Thus making such a separation would be considered as separating terumah from higher quality produce for lower quality produce which is permitted as stated above. but not from olives that will be pickled for olives from which oil will be squeezed.72For this is considered as separating terumah from lower quality produce for higher quality produce which is forbidden as an initial preference, as stated in Halachah 3. [One may separate terumah] from wine that has not been boiled for wine that has been boiled,73Boiling detracts from wine's flavor. Hence, one is separating terumah from higher quality produce for lower quality produce. but not from [wine] that has been boiled for [wine] that has not been boiled. [One may separate terumah] from [wine that is] clear74I.e., does not have dregs suspended in it. for [wine that is] not clear, but not from [wine that is] not clear for wine [that is] clear.
[One may separate terumah] from a specific number of fresh figs for a specific number of dried figs75When a priest is present and he is being given the figs, fresh figs are obviously considered as more desirable than dried figs. and from a measure of dried figs for a measure of fresh figs,76For the measure of dried figs will be more compact than that of fresh figs. Thus the priest will be receiving a greater quantity of fruit. but not from a measure of fresh figs for a measure of dried figs, nor for a specific number of dried figs for a specific number of fresh figs. [The rationale for all the above is that] one should always separate terumah in a generous manner.77E.g., giving and produce of a higher quality or giving more ample portions.
One may separate terumah from kernels of wheat for bread,78Kernels of wheat are considered as having an advantage over grain, because a) one can use them for whatever purposes one desires, and b) they store longer than grain. but not from bread for kernels of wheat according to the appropriate calculations.79i.e., how many kernels of wheat it would take to produce this quantity of bread. In all the above situations, if one separated terumah [when it was stated that one should not], the separation is effective.80As stated in Halachah 3. The Shulchan Aruch (loc. cit.:63) states that in the present era when the produce separated as terumah is discarded, there is no need to show these precautions.

הלכה יט
אֵין תּוֹרְמִין שֶׁמֶן עַל הַזֵּיתִים הַנִּכְתָּשִׁין. וְלֹא יַיִן עַל עֲנָבִים הַנִּדְרָכוֹת שֶׁזֶּה דּוֹמֶה לְתוֹרֵם מִדָּבָר שֶׁנִּגְמְרָה מְלַאכְתּוֹ עַל דָּבָר שֶׁלֹּא נִגְמְרָה מְלַאכְתּוֹ. וְאִם תָּרַם תְּרוּמָתוֹ תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם מִן הַזֵּיתִים וְהָעֲנָבִים בִּפְנֵי עַצְמָן. הָרִאשׁוֹנָה מְדַמַּעַת בִּפְנֵי עַצְמָהּ וְהָאוֹכְלָהּ חַיָּב עָלֶיהָ כִּשְׁאָר תְּרוּמוֹת גְּמוּרוֹת אֲבָל לֹא מִן הַשְּׁנִיָּה:
כסף משנה
19.
We do not separate terumah from oil for olives that are being pressed, nor [do we separate terumah] from wine for grapes that are being tread, for this resembles separating terumah from produce for which all work has been completed for produce for which the work has not been completed.81See Halachah 4 above. In the situation described in that halachah, the person is not required to make a second separation, because our Sages felt that people understood that terumah should not be separated in such an instance and did not see the need for an additional safeguard. In this situation, since work with that produce has already begun, they felt that a safeguard was necessary (Rambam LeAm). Other commentaries offer different rationales for the difference in the rulings. If he did separate terumah [in such a situation], the produce separated is considered as terumah, but he must separate terumah from the olives and the grapes from them themselves.82I.e., after he completed pressing the olives or treading the grapes, he should separate terumah a second time for that oil or wine [the Rambam's Commentary to the Mishnah (Terumot 1:8)].
[When mixed with other produce,] the first creates a situation of dimua83A mixture of terumah and ordinary produce, as mentioned in Chapter 13, Halachah 2. alone.84I.e., even if it is not mixed with the produce separated a second time in contrast to the situation described in Halachah 22. The rationale is that, in this instance, after the fact, the first separation is effective, as stated in Halachah 4 above. One who eats it is liable for it, as one is liable [for partaking] of other terumah that is clearly defined as such.85See Chapter 6, Halachah 6. This does not apply with regard to the second terumah [separated].86For it is terumah only as a result of Rabbinic decree.

הלכה כ
מִי שֶׁתָּרַם שֶׁמֶן עַל זֵיתִים שֶׁדַּעְתּוֹ לְאָכְלָן. אוֹ זֵיתִים עַל זֵיתִים וְדַעְתּוֹ עַל הַכּל לַאֲכִילָה. אוֹ שֶׁתָּרַם יַיִן עַל עֲנָבִים שֶׁהֵם לַאֲכִילָה. אוֹ עֲנָבִים עַל עֲנָבִים וְהַכּל לַאֲכִילָה. וְנִמְלַךְ לְדָרְכָן וְדָרַךְ הַזֵּיתִים וְהָעֲנָבִים שֶׁכְּבָר תָּרַם עֲלֵיהֶם. אֵינוֹ צָרִיךְ לַחֲזֹר וְלִתְרֹם:
כסף משנה
20.
When a person separated oil as terumah for olives that he intended to eat or he separated olives for olives when he intended to eat the entire quantity and then changed his mind and decided to press the olives [for oil] and indeed pressed them after separating terumah for them, he is not required to separate terumah again.87For at the time the terumah was separated, the work associated with this produce was completed according to his intent at that time [the Rambam's Commentary to the Mishnah (Terumot 1:9)]. Although he changed his mind, we do not penalize him for making such a decision (Radbaz). [This law also applies if] one separated wine for grapes that he intended to eat or grapes for grapes when he intended to eat the entire quantity and then changed his mind and decided to tread the grapes for wine and indeed had them tread upon after separating terumah for them.

הלכה כא
אֵין תּוֹרְמִין חֹמֶץ עַל יַיִן. אֲבָל תּוֹרְמִין יַיִן עַל חֹמֶץ. שֶׁהַיַּיִן וְהַחֹמֶץ מִין אֶחָד הֵן. (הָיָה בְּלִבּוֹ לִתְרֹם מִן הַיַּיִן עַל הַיַּיִן וְנִמְצָא בְּיָדוֹ חֹמֶץ אֵינָהּ תְּרוּמָה). הָיָה בְּלִבּוֹ לִתְרֹם חֹמֶץ עַל חֹמֶץ וְנִמְצָא הַחֹמֶץ שֶׁתָּרַם יַיִן תְּרוּמָתוֹ תְּרוּמָה:
כסף משנה
21.
We do not separate vinegar as terumah for wine,88For this is equivalent to separating produce of inferior quality for produce of superior quality which should not be done at the outset, as stated in Halachah 3. Nevertheless, if one made such a separation, after the fact, the separation s effective. but we may separate wine as terumah for vinegar, for wine and vinegar are one type of produce.89For when wine sours, it becomes vinegar. If one had the intent of separating wine for wine and it was discovered that what he separated was vinegar, the separation is not effective.90For his separation was made in error and the error lowers the quality of the terumah (Kessef Mishneh). If one had the intent of separating vinegar for vinegar and it was discovered that what he separated was wine, the separation is effective.91For in this instance, his error improves the quality of the terumah (Kessef Mishneh; Siftei Cohen 331:95).

הלכה כב
הַתּוֹרֵם חָבִית שֶׁל יַיִן עַל הַיַּיִן וְנִמְצָא חֹמֶץ אִם יוֹדֵעַ שֶׁהָיְתָה חֹמֶץ עַד שֶׁלֹּא תְּרָמָהּ אֵינָהּ תְּרוּמָה. וְאִם אַחַר שֶׁתְּרָמָהּ הֶחְמִיצָה הֲרֵי זוֹ תְּרוּמָה. וְאִם סָפֵק תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם. וְכֵן הַתּוֹרֵם קִשּׁוּת וְנִמְצֵאת מָרָה אֲבַטִּיחַ וְנִמְצָא סָרוּחַ אוֹ שֶׁנִּמְצְאוּ נְקוּרִין. תָּרַם חָבִית שֶׁל יַיִן וְנִמְצֵאת מְגֻלָּה שֶׁאָסוּר לִשְׁתּוֹתָהּ תְּרוּמָה וְיַחֲזֹר וְיִתְרֹם שְׁנִיָּה. וְאֵין אַחַת מִשְּׁתֵּיהֶן מְדַמַּעַת בִּפְנֵי עַצְמָהּ. וְהָאוֹכֵל אַחַת מִשְּׁתֵּיהֶן אֵינוֹ חַיָּב חֹמֶשׁ:
כסף משנה
22.
[The following rules apply when a person] separates a barrel of wine as terumah for wine and it is discovered to be vinegar. If it was known to be vinegar before it was separated, the separation is not effective.92As in the previous halachah, this is speaking about an instance where the person had the intent of separating wine as terumah. If, however, he intended to separate vinegar, the separation is effective after the fact (Radbaz). If it became vinegar after it was designated as terumah, the separation is effective.93For at the time of the separation, wine was separated as the person intended. The fact that it soured afterwards is not his responsibility. If there is a doubt, the separation is effective,94Because of the doubt involved. Perhaps it had not become sour at the time it was separated and the first separation was effective. but he should make a second separation.95For perhaps it was sour before the first separation was made and thus the separation was not effective. The same laws apply when one separates squash as terumah and it is discovered to be bitter or one separates a watermelon as terumah and it has become spoiled96I.e., its contents are not fit for consumption [the Rambam's Commentary to the Mishnah (Terumot 3:1)]. or perforated.97In which instance, we fear that the holes were made by a poisonous snake which deposited its venom in the watermelon. If he separated a barrel of wine as terumah and it was discovered to have been left open in which instance, it is forbidden to drink it,98Because of the danger involved. We fear that perhaps a poisonous snake or the like deposited venom in it (Hilchot Rotzeach UShemirat Nefesh 12:2). it is terumah, but he should make a second separation.99This appears to be speaking about a situation in which he is unsure when the snake drank from the wine before the terumah was separated or not.
[In all these situations, when mixed with other produce,] neither of the two [portions separated as terumah] creates a situation of dimua alone.100I.e., since we are unsure which of the separations is effective, neither alone is considered as terumah. Nor is a person who eats only one of the two obligated to pay a fifth.101As is required when one partakes of terumah inadvertently, as stated in Chapter 6, Halachah 6.

הלכה כג
כֵּיצַד. נָפְלָה אַחַת מֵהֶן עַל הַחֻלִּין אֵינָהּ מְדַמַּעַת. נָפְלָה שְׁנִיָּה לְמָקוֹם אַחֵר אֵינָהּ מְדַמַּעְתָּהּ. נָפְלוּ שְׁתֵּיהֶן לְמָקוֹם אֶחָד מְדַמְּעוֹת בַּקְּטַנָּה שֶׁבִּשְׁתֵּיהֶן. וְכֵן אִם אָכַל זָר שְׁתֵּיהֶן מְשַׁלֵּם בַּקְּטַנָּה שֶׁבִּשְׁתֵּיהֶן וְחֻמְשָׁהּ. וְכֵיצַד הוּא עוֹשֶׂה בִּשְׁתֵּיהֶן נוֹתְנָן לְכֹהֵן אֶחָד וְנוֹטֵל מִן הַכֹּהֵן דְּמֵי הַגְּדוֹלָה:
כסף משנה
23.
What is implied? If one [of the two portions separated as terumah] fell into ordinary produce, it does not cause it to be considered as dimua. If the other [portion] fell into other produce, it does not cause it to be considered as dimua.102Although one of the two is obviously dimua, since we do not know which one, we rule leniently with regard to both. If, however, both fell into the same produce, it is considered as dimua according to the size of the smaller of the two.103In this instance, the terumah has obviously become mixed with the ordinary produce. Nevertheless, since we do not know which of the two is terumah, we require him to be concerned only with the smaller amount.
Similarly, if a person other than a priest ate both of them, he should make restitution for the smaller one and its additional fifth.104As is required when one partakes of terumah inadvertently, as stated in Chapter 6, Halachah 6. What should he do with the two [portions separated]?105Although both must be considered as terumah, because he does not have a definite obligation to give either to a priest. He should give them to one priest and take the value of the greater portion from him.106For he is obligated to give at least the value of the smaller portion to the priest; for the remainder the priest must pay. Nevertheless, the price he pays for produce designated as terumah is less than that than he would pay for ordinary produce.

הלכה כד
הַבּוֹדֵק אֶת הֶחָבִית וְהִנִּיחָהּ לְהַפְרִישָׁהּ תְּרוּמָה עַל אֲחֵרִים עַד שֶׁתֵּעָשֶׂה כֻּלָּהּ תְּרוּמָה וְיִתְּנֶנָּה לַכֹּהֵן. וּלְאַחַר זְמַן בְּדָקָהּ וּמְצָאָהּ חֹמֶץ. מֵעֵת שֶׁבְּדָקָהּ תְּחִלָּה עַד שְׁלֹשָׁה יָמִים וַדַּאי יַיִן וְכָל יַיִן שֶׁחָשַׁב אוֹתָן הַיָּמִים שֶׁהַתְּרוּמָה שֶׁלּוֹ בְּחָבִית זוֹ הֲרֵי הוּא מְתֻקָּן. מִכָּאן וְאֵילָךְ סָפֵק וְצָרִיךְ לְהַפְרִישׁ מִמֶּנּוּ תְּרוּמָה שְׁנִיָּה:
כסף משנה
24.
[The following rules apply when a person] checks a barrel [of wine]107To make sure that it had not become vinegar. and then leaves it to separate terumah [from it] on other [wine] until it becomes terumah in its entirety, [at which point,] he would give it to the priest.108I.e., the person took a barrel of wine and set it aside with the intent that he would consider an appropriate measure of wine from it as terumah for all the wine that he would continue to produce until the barrel became terumah in its entirety. After a certain time, he checked the barrel again and discovered that it had become vinegar.109Thus there is a question regarding the status of the produce that he separated previously. For if the barrel had become vinegar earlier, the separation of terumah would not be effective, as stated above. [We rule that the wine] certainly remained wine for three days after the inspection. [The obligations for terumah] have certainly been met for all of the wine for which he considered the wine in the barrel as its terumah during those [three days]. From that time afterwards, there is a doubt [whether the wine had already turned to vinegar] and a second separation [of terumah] must be made.110As explained above.

הלכה כה
בִּשְׁלֹשָׁה פְּרָקִים צָרִיךְ לִבְדֹּק אֶת הַיַּיִן שֶׁהִנִּיחוֹ לִפְרשׁ עָלָיו שֶׁמָּא הֶחְמִיץ. וְאֵלּוּ הֵן. בְּקַדִּים שֶׁל מוֹצָאֵי הֶחָג. וּבְהוֹצָאַת הַסְּמָדַר. וּבִשְׁעַת כְּנִיסַת מַיִם לַבֹּסֶר. וְיַיִן מִגִּתּוֹ מַפְרִישִׁין עָלָיו בְּחֶזְקַת שֶׁהוּא יַיִן [עַד] אַרְבָּעִים יוֹם:
כסף משנה
25.
At three times [during the year], it is necessary to check the wine that one set aside to separate terumah from111I.e., the person took a barrel of wine and set it aside with the intent that he would consider an appropriate measure of wine from it as terumah for all the wine that he would continue to produce until the barrel became terumah in its entirety. lest it have become vinegar. They are: When the east wind blows after the Sukkos holiday, when grapes form,112When the flowers of the grape vine fall and the actual fruit begins to form. when fluid begins to enter the unripened grapes.113When the juice of the grape begins to collect within the fruit.
Since these are times of change for grapes, there is also a possibility that wine will also be affected.
[When one has wine] from the vat,114I.e., freshly squeezed grape juice. he may use it for the separation [of terumah] for 40 days with the presumption that it is still wine.115For it is unlikely to turn into vinegar before then.

הלכה כו
הַמַּנִּיחַ פֵּרוֹת לִהְיוֹת מַפְרִישׁ עֲלֵיהֶן עַד שֶׁיֵּעָשׂוּ תְּרוּמָה אַף עַל פִּי שֶׁאֵין מַפְרִישִׁין לְכַתְּחִלָּה אֶלָּא מִן הַמֻּקָּף אִם הִפְרִישׁ הֲרֵי הֵן בְּחֶזְקַת קַיָּמִין. מְצָאָן שֶׁאָבְדוּ הֲרֵי זֶה חוֹשֵׁשׁ לְכָל מַה שֶּׁתִּקֵּן שֶׁמָּא לֹא הִפְרִישׁ עֲלֵיהֶן אֶלָּא אַחַר שֶׁאָבְדוּ לְפִיכָךְ מַפְרִישׁ תְּרוּמָה שְׁנִיָּה:
כסף משנה
26.
[The following rules apply when a person] sets aside produce to separate terumah from until [the entire amount] becomes terumah.116I.e., he sets aside produce to serve the same purpose as the wine mentioned in Halachah 24. Although as an initial preference, one should separate terumah only from the same collection of produce,117See Chapter 3, Halachah 17. As explained there, after the fact, such a separation is acceptable. if one separates terumah [in such a manner], we operate under the presumption that the produce continues to exist. If he discovers that they perished, he should entertain doubts that all [the produce for which he thought he separated terumah is in fact tevel].118I.e., he should entertain the possibility that perhaps from the outset, the separation of the terumah was not acceptable. For perhaps, he did not make any separation until [the produce set aside] perished. Therefore he should separate terumah a second time for them.119As explained in Halachah 22.

זרעים הלכות תרומות פרק ה
Zeraim Terumos Chapter 5