Halacha

הלכה א
הַזּוֹרֵעַ שְׁנֵי מִינֵי תְּבוּאָה אוֹ שְׁנֵי מִינֵי יְרָקוֹת עִם זֶרַע הַכֶּרֶם הֲרֵי זֶה לוֹקֶה שְׁתַּיִם. אַחַת מִשּׁוּם (ויקרא יט יט) "שָׂדְךָ לֹא תִזְרַע כִּלְאָיִם" וְאַחַת מִשּׁוּם (דברים כב ט) "לֹא תִזְרַע כַּרְמְךָ כִּלְאָיִם":
כסף משנה
1.
When a person sows two types of grain or two types of vegetables1The wording of the prooftext implies that one is sowing mixed species - i.e., two species that are themselves kilayim - in a vineyard, i.e., together with grape seeds (Radbaz). together with [grape] seeds, he is liable for two sets of lashes:2Provided he is given a warning for each of the prohibitions (ibid.). one for [violating the prohibition (Leviticus 19:19 ]: "You shall not sow your field with mixed species,"3As explained in Chapter 1. and one for [violating the prohibition (Deuteronomy 22:9 ]:4I.e., he transgresses a negative commandment, included as one of the 365 negative commandments by Sefer HaMitzvot (negative commandment 216) and Sefer HaChinuch (mitzvah 548). "You shall not sow your vineyard with mixed species."

הלכה ב
וְאֵינוֹ לוֹקֶה מִשּׁוּם זוֹרֵעַ כִּלְאֵי הַכֶּרֶם עַד שֶׁיִּזְרַע בְּאֶרֶץ יִשְׂרָאֵל חִטָּה וּשְׂעוֹרָה וְחַרְצָן בְּמַפּלֶת יָד. וְכֵן אִם חִפָּה אוֹתָם בְּעָפָר לוֹקֶה. וְכֵן אִם זָרַע שְׁנֵי מִינֵי יָרָק וְחַרְצָן אוֹ זֶרַע אֶחָד יָרָק וְזֶרַע אֶחָד מִין תְּבוּאָה וְחַרְצָן בְּמַפּלֶת יָד הֲרֵי זֶה לוֹקֶה:
כסף משנה
2.
A person does not receive lashes for sowing kilayim in a vineyard unless he sows a handful of wheat, barley,5Not only wheat and barley, but all five species of grain are considered as mixed species when sown with grapes and forbidden according to Scriptural Law. and grape seed in Eretz Yisrael.6For the only concept of kilayim that applies with regard to crops in the Diaspora is the prohibition against grafting different species of trees. The prohibition against mixed crops, like all the other laws concerning the crops of Eretz Yisrael, do not apply in the Diaspora. Similarly, one who covers such seeds with earth is worthy of lashes. And one who sows two types of vegetable seeds or a vegetable seed, a grain seed, and a grape seed from one hand is worthy of lashes.

הלכה ג
וְאֵינוֹ חַיָּב מִן הַתּוֹרָה אֶלָּא עַל קַנְבּוֹס וְלוּף וְכַיּוֹצֵא בָּהֶן מִזְּרָעִים שֶׁנִּגְמָרִים עִם תְּבוּאַת הַכֶּרֶם אֲבָל שְׁאָר הַזְּרָעִים אֲסוּרִים מִדִּבְרֵיהֶם. וְכֵן אָסוּר מִדִּבְרֵיהֶם לִזְרֹעַ כִּלְאֵי הַכֶּרֶם בְּחוּצָה לָאָרֶץ:
כסף משנה
3.
He is not liable according to Scriptural Law unless [he sows] hemp and wild onions or the like from seeds that will mature together with the produce of the vineyard.7These species, like grapes, require three years before their produce appears. For the prohibition against mixed species to apply, the produce must resemble that of the grape vine.
In his Commentary to the Mishnah (Kilayim 2:5), the Rambam writes that he does not see how it is possible for there to be a vegetable plant that does not produce fruit for three years. That is a common phenomenon for trees and vines, but not for vegetables. He writes that these species of vegetables do remain in the ground for several years and continue to produce fruit and that appears to be the Rambam's intent.
Other types of seeds are forbidden according to Rabbinic decree. Similarly, according to Rabbinic decree, it is forbidden to sow kilayim in a vineyard in the Diaspora.

הלכה ד
וְלָמָּה אָסְרוּ כִּלְאֵי הַכֶּרֶם [בְּחוּצָה לָאָרֶץ וְלֹא אָסְרוּ כִּלְאֵי זְרָעִים] מִפְּנֵי שֶׁכִּלְאֵי הַכֶּרֶם חֲמוּרִין הֵם שֶׁאִם נִזְרְעוּ בְּאֶרֶץ יִשְׂרָאֵל הֲרֵי הֵן אֲסוּרִין בַּהֲנָאָה וְכֵיוָן שֶׁהֵן אֲסוּרִין בַּהֲנָאָה בָּאָרֶץ אָסְרוּ לְזָרְעָן בְּחוּצָה לָאָרֶץ:
כסף משנה
4.
Why did [the Sages] forbid planting mixed species in a vineyard in the Diaspora, but not mixed species in a field?8As stated in Chapter 1, Halachah 3. Because [the prohibition against] mixed species in a vineyard is more severe. For if they were to be sown in Eretz Yisrael, it would be forbidden to benefit from them.9As mentioned in Hilchot Ma'achalot Assurot 10:6, Deuteronomy 22:9 states: ...Lest the fullness of the seed which you sowed and the produce of the vineyard become hallowed.' ['Becom[ing] hallowed'] means being set apart and forbidden."
In contrast, mixed species in the field are forbidden to be eaten, but it is permitted to benefit from them, as stated in Chapter 1, Halachah 7.
Since it is forbidden to benefit from them in Eretz Yisrael, it is forbidden to sow them in the Diaspora.

הלכה ה
וְאֵין עוֹדְרִין עִם הַנָּכְרִי בְּכִלְאַיִם אֲבָל עוֹקְרִין עִמּוֹ כְּדֵי לְמַעֵט הַתִּפְלָה:
כסף משנה
5.
We may not hoe with a gentile with mixed produce,10This applies even on land belonging to a gentile. The Radbaz maintains that, according to the Rambam, this prohibition applies even on land belonging to a gentile in the Diaspora. Since it is forbidden for a Jew to plant such crops there according to Rabbinic Law, it is forbidden to help a gentile. but one may uproot the produce11With the intent of destroying it. with him in order to eliminate the undesirable substances.12The Radbaz asks: Since mixed substances that grow on a gentile's land are not prohibited, why are they referred to as undesirable substances? He explains that since they are forbidden when growing on a Jew's land, they are considered as undesirable even when growing on a gentile's land.

הלכה ו
אֵין אָסוּר מִשּׁוּם כִּלְאֵי הַכֶּרֶם אֶלָּא מִינֵי תְּבוּאָה וּמִינֵי יְרָקוֹת בִּלְבַד. אֲבָל שְׁאָר מִינֵי זְרָעִים מֻתָּר לְזָרְעָם בְּכֶרֶם וְאֵין צָרִיךְ לוֹמַר שְׁאָר אִילָנוֹת:
כסף משנה
6.
The prohibition against mixed species in a vineyard applies only to species of grain and species of vegetables. Other types of plants,13I.e., plants that do not produce edible produce. This applies even according to Rabbinic Law (Kessef Mishneh). See Halachah 19 for illustrations of this principle. by contrast, are permitted to be sown in a vineyard. Needless to say, [this applies with regard] to other trees.14I.e., all types of trees may be planted in a vineyard.

הלכה ז
אָסוּר לִזְרֹעַ יְרָקוֹת אוֹ תְּבוּאָה בְּצַד הַגְּפָנִים אוֹ לִטַּע גֶּפֶן בְּצַד הַיָּרָק אוֹ תְּבוּאָה. וְאִם עָשָׂה כֵּן אַף עַל פִּי שֶׁאֵינוֹ לוֹקֶה הֲרֵי זֶה קִדֵּשׁ וְנֶאֶסְרוּ שְׁנֵיהֶם בַּהֲנָאָה הַיָּרָק אוֹ הַתְּבוּאָה אוֹ הַגְּפָנִים. וְשׂוֹרְפִין אֶת שְׁנֵיהֶן שֶׁנֶּאֱמַר (דברים כב ט) "פֶּן תִּקְדַּשׁ הַמְלֵאָה הַזֶּרַע". וַאֲפִלּוּ הַקַּשׁ שֶׁל תְּבוּאָה וְהָעֵצִים שֶׁל גְּפָנִים הָאֵלּוּ אֲסוּרִין בַּהֲנָאָה וְשׂוֹרְפִין אוֹתָם וְלֹא יַסִּיק בָּהֶן תַּנּוּר וְכִירַיִם וְלֹא יְבַשֵּׁל בָּהֶם בְּעֵת שְׂרֵפָתָן:
כסף משנה
7.
It is forbidden to sow vegetables or grain next to vines or to plant a vine next to vegetables or grain.15The Beit Yosef (Yoreh De'ah 296) states that the Rambam's wording implies that only one species of vegetable or grain is present. Although Halachah 1 states that to be liable for lashes, he must sow two mixed species together, a prohibition is involved when even one is present. If one does this, although he is not liable for lashes,16For as stated in Halachah 2, he is not liable for lashes unless he sows the mixed species together. [the produce] is hallowed and it is forbidden to benefit from both the grain or vegetables and the vines.17From the Rambam's wording, it is clear that he does not consider this as a Rabbinic safeguard, but rather the violation of a Scriptural prohibition. They must both be burnt, as [Deuteronomy 22:9] states: "Lest the fullness of the seed... become hallowed."
It is forbidden to benefit from even the straw of this grain and the wood from these vines.18I.e., the prohibition does not apply only to the produce, but to the plants themselves. See the gloss of the Radbaz. They must be burnt. One should not use them as fuel for an oven19Moreover, if a new oven is fired with them, it is forbidden to benefit from the oven itself. For firing a new oven completes it (Pesachim 26a). or a range and one should not [use them] for cooking while they are being burnt.

הלכה ח
אֶחָד הַנּוֹטֵעַ וְאֶחָד הַמְקַיֵּם כֵּיוָן שֶׁרָאָה כִּלְאַיִם צָמְחוּ בְּכַרְמוֹ וְהִנִּיחָם הֲרֵי זֶה קִדֵּשׁ. וְאֵין אָדָם מְקַדֵּשׁ דָּבָר שֶׁאֵינוֹ שֶׁלּוֹ. לְפִיכָךְ הַמְסַכֵּךְ גַּפְנוֹ עַל גַּבֵּי תְּבוּאָתוֹ שֶׁל חֲבֵרוֹ קִדֵּשׁ גַּפְנוֹ וְלֹא נִתְקַדְּשָׁה הַתְּבוּאָה. סִכֵּךְ גֶּפֶן חֲבֵרוֹ עַל תְּבוּאָתוֹ קִדֵּשׁ תְּבוּאָה וְלֹא קִדֵּשׁ גֶּפֶן חֲבֵרוֹ. סִכֵּךְ גֶּפֶן חֲבֵרוֹ עַל תְּבוּאַת חֲבֵרוֹ לֹא קִדֵּשׁ אֶחָד מֵהֶן. וּמִפְּנֵי זֶה הַזּוֹרֵעַ כַּרְמוֹ בַּשְּׁבִיעִית לֹא קִדֵּשׁ:
כסף משנה
8.
[The prohibition applies equally] whether one plants or maintains kilayim; i.e., one saw that mixed substances grew in his vineyard and he left them [to grow], they become hallowed.20The owner of the field is not, however, liable for lashes, because he did not perform a deed.
A person may not hallow an article that is not his.21We find this principle in several other contexts (e.g., Hilchot Nazirut 9:9; Hilchot Arachin 4:26). Nevertheless, in those instances, the consecration of the article does not reflect a physical change in its state, but rather its designation as being holy. It is logical to conceive that only the owner of an article can make such a designation. In the present instance, by contrast, the different species of produce become hallowed because of the fact that they grow together. Seemingly, it makes no difference why they grow together, whether they were planted by the owner or by another person. Indeed, if a person puts milk into a pot cooking with meat belonging to his colleague, the food becomes prohibited.
For this reason, although the Rambam accepts the above principle in other contexts. He found it problematic with regard to kilayim. Thus in his Commentary to the Mishnah (Kilayim 7:4), he originally favored the opinions which maintain that the above principle does not apply in this instance. Only later in life did he change his view and rule, as above, that it does apply. According to Rav Kappach, at that time, he also amended his Commentary to the Mishnah.
Therefore if a person draped his vine over grain belonging to a colleague, he causes his vine to be hallowed, but not the grain. If he draped a vine belonging to a colleague over his grain, he causes his grain to be hallowed, but not his colleague's vine. If he draped a vine belonging to a colleague over grain belonging to a colleague, he does not cause either of them to become hallowed. For this reason, when a person sows [kilayim] in his vineyard in the Sabbatical year, he does not cause it to be hallowed.22For in the Sabbatical year, the field is not his own. Instead, it is ownerless. As above, in this instance as well, the Rambam deviated from his original ruling in his Commentary to the Mishnah (loc. cit.:5).
The Radbaz notes that the above ruling applies to the produce, but not the wood growing in the vineyard, because the wood does not become ownerless. Therefore it is forbidden.

הלכה ט
הָרוֹאֶה כִּלְאַיִם בְּכֶרֶם חֲבֵרוֹ וְקִיְּמָן הֲרֵי זֶה הָרוֹאֶה אָסוּר בַּהֲנָיָתָן וְכָל אָדָם מֻתָּרִין בָּהֶן. וְאִלּוּ קִיְּמָן בַּעַל הַכֶּרֶם הָיָה מְקַדֵּשׁ אוֹתָן לְכָל אָדָם כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
9.
When a person23The Ra'avad (based on the Jerusalem Talmud, Kilayim 7:5) interprets this as referring to a situation where the person is working for the owner of the field. Otherwise, he maintains there is no reason to rule that he should be forbidden to benefit. Rav Yosef Corcus and the Radbaz explain the Rambam's ruling. Rav Yosef Corcus states that it applies to a person who has the right to enter his colleague's field even thought he is not working there (see also Turei Zahav 296:3). Otherwise, he would not have any effect on it, even for himself. The Radbaz states that the Rambam's ruling applies even to a person at large. Since he did not notify the owner about the problem, it is as if he took a vow to personally consider the produce as forbidden. sees mixed species [growing] in a vineyard belonging to a colleague and maintained them, that observer is forbidden to benefit from them. Every other person is permitted. Were the owner of the vineyard to have maintained them, they would be hallowed for all people as explained.

הלכה י
הָאַנָּס שֶׁזָּרַע כִּלְאַיִם בְּכֶרֶם חֲבֵרוֹ אִם נִשְׁתַּקְּעוּ הַבְּעָלִים אַף עַל פִּי שֶׁלֹּא נִתְיָאֲשׁוּ הֲרֵי זֶה קִדֵּשׁ מִן הַתּוֹרָה. וְאִם לֹא נִשְׁתַּקְּעוּ הַבְּעָלִים אַף עַל פִּי שֶׁנִּתְיָאֲשׁוּ אֵינוֹ מְקַדֵּשׁ אֶלָּא מִדִּבְרֵי סוֹפְרִים:
כסף משנה
10.
[The following laws apply when] a man of force24In the time of the Roman occupation, it was common for landed property to be taken by force. Our Sages addressed the possible halachic problems that arise in such a situation. sowed kilayim in a vineyard belonging to another person. If the owner hides out of fear,25Our translation is based on the Rambam's Commentary to the Mishnah (Kilayim 7:6). Others interpret the term as meaning that the land is no longer referred to as belonging to the original owner. even though he does not despair over [ultimately receiving his property], [the produce] becomes hallowed according to Scriptural Law.26The Radbaz explains that since the owner is forced to hide, even though in his own heart, he hopes to have the land returned, it is as if he has already given up hope (Radbaz). Although generally, we follow the ruling that land cannot be stolen (Hilchot Gezeilah 8:14), but instead, is always considered as belonging to the original owner, in this instance, because of the severity of the prohibition against kilayim, we rule stringently. If he does not hide, even though he does despair [the produce] becomes hallowed only according to Rabbinic Law.

הלכה יא
הָרוּחַ שֶׁעָקְרָה פְּאֵרוֹת הַגֶּפֶן וְשִׁלְּחָה אוֹתָן עַל הַתְּבוּאָה יִגְדֹּד אוֹתָן מִיָּד. וְאִם אֵרְעוֹ אֹנֶס וְלֹא סִלְּקָן הֲרֵי אֵלּוּ מֻתָּרִין וְלֹא נִתְקַדְּשׁוּ:
כסף משנה
11.
When wind uproots branches of a vine and blows them against grain, one should remove27Our translation is based on authentic manuscripts and early printings of the Mishneh Torah. It also follows the Rambam's Commentary to the Mishnah (according to Rav Kappach's version). The standard printed text of the Mishneh Torah - and also that followed by the Kessef Mishneh - follows a different version. In all cases, the basic intent remains the same. them immediately. If he did not remove them28I.e., and in the time he did not remove them, they grew 1/200th, as stated in Halachah 22. due to forces beyond his control, they are permitted and they do not become hallowed.29For, as evident from Halachah 21, a person does not cause produce to be considered kilayim unless he willfully allows the mixed species to grow.

הלכה יב
אַנָּס שֶׁזָּרַע הַכֶּרֶם כְּשֶׁיָּצָא הָאַנָּס יִקְצֹר הַזֶּרַע מִיָּד וַאֲפִלּוּ בְּחֻלּוֹ שֶׁל מוֹעֵד. וְאִם לֹא מָצָא פּוֹעֲלִין יוֹסִיף לָהֶן עַד שְׁלִישׁ בִּשְׂכָרָן. בִּקְּשׁוּ מִמֶּנּוּ יוֹתֵר מִכֵּן אוֹ שֶׁלֹּא מָצָא פּוֹעֲלִים הֲרֵי זֶה מְבַקֵּשׁ בְּנַחַת וְקוֹצֵר. וְאִם נִשְׁתַּהָא הַזֶּרַע עַד שֶׁהִגִּיעַ לְעוֹנַת שֶׁיִּקְדַּשׁ הֲרֵי זֶה יִקְדַּשׁ וְיֵאָסְרוּ שְׁנֵיהֶם:
כסף משנה
12.
[The following laws apply when] a man of force30In the time of the Roman occupation, it was common for landed property to be taken by force. Our Sages addressed the possible halachic problems that arise in such a situation. sowed [kilayim] in a vineyard [and then departed, leaving the vineyard to its original owner]. When the man of force departs, [the owner] should harvest the crops immediately,31Lest he be liable for maintaining kilayim.even during Chol HaMoed.32The intermediate days of a festival, when there are restrictions against performing work in one's fields (see Hilchot Sh'vitat Yom Tov, ch. 7). Nevertheless, in this instance, he is required to do so, to avoid the violation of the prohibition against kilayim. If one cannot find workers, he should add even a third to their wages.33In his Commentary to the Mishnah (Kilayim 7:6), the Rambam gives an example. If the worker's wage was normally three zuz a day, he should be paid four. If they demanded more than that or was unable to find workers, he may continue searching without pressure and harvest [the produce]. If the produce remained until it reached the point that it hallows [the vineyard],34I.e., it grows 1/200th. it is hallowed and both species are forbidden.

הלכה יג
מֵאֵימָתַי תְּבוּאָה אוֹ יָרָק מִתְקַדְּשִׁין מִשֶּׁיַּשְׁרִישׁוּ. עֲנָבִים מִשֶּׁיֵּעָשׂוּ כְּפוֹל הַלָּבָן. שֶׁנֶּאֱמַר (דברים כב ט) "הַמְלֵאָה הַזֶּרַע אֲשֶׁר תִּזְרָע וּתְבוּאַת הַכָּרֶם" עַד שֶׁיִּזְרַע זֶה וְיִהְיֶה זֶה תְּבוּאָה. אֲבָל תְּבוּאָה שֶׁיָּבְשָׁה כָּל צָרְכָּהּ וַעֲנָבִים שֶׁבָּשְׁלוּ כָּל צָרְכָּן אֵינָן מִתְקַדְּשׁוֹת. [כֵּיצַד. תְּבוּאָה שֶׁיָּבְשָׁה כָּל צָרְכָּהּ וּבָא וְנָטַע גֶּפֶן בְּתוֹכָהּ וְכֵן עֲנָבִים שֶׁבָּשְׁלוּ כָּל צָרְכָּן וְזָרַע תְּבוּאָה אוֹ יָרָק בְּצִדָּן אַף עַל פִּי שֶׁזֶּה אָסוּר אֵינָן מִתְקַדְּשׁוֹת]:
כסף משנה
13.
When do grain or vegetables become hallowed? When [the plants] develop roots. [When do] grapes? When they reach the size of a white bean, as [implied by Deuteronomy 22:9]: "Lest the fullness of the seed which you sowed and the produce of the vineyard become hallowed;" [i.e., the prohibition applies when] one sows this35Wheat or vegetables. and this36The grapes. becomes produce. If, however, the grain37Before grain is ready to be harvested, the kernels dry out and harden. has already dried to the degree necessary or grapes had matured to their full extent, they do not become hallowed.38In his Commentary to the Mishnah (ibid.:7), the Rambam explains that the prooftext describing the prohibition speaks of "the seed" and "the produce." The Hebrew terms imply produce that is in the process of developing and not produce that has already developed fully and is ready to be harvested.
What is implied? When grain has already dried to the degree necessary and then one planted a vine in their midst or grapes had matured to their full extent and one planted grain or a vegetable next to them, although this is forbidden, they do not become hallowed.

הלכה יד
כֶּרֶם שֶׁלֹּא הִגִּיעוּ עֲנָבָיו לִהְיוֹת כְּפוֹל הַלָּבָן אֶלָּא עֲדַיִן הֵן בֹּסֶר וְזָרַע בְּתוֹכוֹ יָרָק אוֹ תְּבוּאָה וְהִשְׁרִישׁוּ הֲרֵי זֶה לֹא קִדֵּשׁ. וְאַף עַל פִּי כֵן קוֹנְסִין אוֹתוֹ וְאוֹסְרִין הַזֶּרַע. אֲבָל הַבֹּסֶר מֻתָּר וְאִם עָקַר הַזֶּרַע קֹדֶם שֶׁיֵּעָשׂוּ הָעֲנָבִים כְּפוֹל הַלָּבָן הֲרֵי זֶה מֻתָּר בַּהֲנָיָה. מִקְצָתָן נַעֲשׂוּ כְּפוֹל הַלָּבָן וּמִקְצָתָן לֹא נַעֲשׂוּ. אֶת שֶׁנַּעֲשׂוּ נִתְקַדְּשׁוּ וְאֶת שֶׁלֹּא נַעֲשׂוּ מֻתָּרִין:
כסף משנה
14.
[The following rules apply in] a vineyard whose grapes have not grown to the size of a white bean, but are still underdeveloped. If one sowed vegetables or grain there and they took root, they are not hallowed.39I.e., according to Scriptural Law, neither the vines, nor the grain or the vegetables are forbidden. Nevertheless, he is penalized and we forbid the growths.40According to Rabbinic decree. Not only may one not partake of them, it is forbidden to benefit from them. The underdeveloped grapes, by contrast, are permitted.41The Ra'avad states that it is permitted to benefit from the produce of the vine, implying that it is forbidden to partake of it. The Radbaz and the Kessef Mishneh, however, differ and maintain that it is permitted even to partake of it. If one uprooted the growths before the grapes became the size of a white bean, it is permitted to benefit from them.42The Radbaz and the Kessef Mishneh state that this ruling appears to contradict the Rambam's statements made previously, that "he is penalized and we forbid the growths," implying that it is forbidden to benefit from them. They each suggest possible resolutions of the issue.
If some of [the grapes] have reached that size and some have not, those which have are hallowed and those which have not are not.43This is speaking about a situation where the grain or the vegetables have taken root. The grain or the vegetables are forbidden, as above.

הלכה טו
עֲנָבִים שֶׁנַּעֲשׂוּ כְּפוֹל הַלָּבָן וְזָרַע בְּצִדָּן תְּבוּאָה אוֹ מִינֵי יְרָקוֹת וְלָקַט הַזֶּרַע קֹדֶם שֶׁיַּשְׁרִישׁ הֲרֵי זֶה מֻתָּר בַּהֲנָאָה וְאִם הִשְׁרִישׁ אָסוּר:
כסף משנה
15.
When grapes have grown to the size of a white bean and one planted grain or types of vegetables at their side and reaped the growths before they became rooted, it is permitted to benefit from them.44It appears that, according to the Rambam, it is forbidden to partake of their produce immediately. The Ra'avad permits one to partake of it. His rationale is that since they did not take root, it is as if they were never planted. The Radbaz explains that the prohibition against partaking of the produce is a Rabbinic safeguard. If they became rooted, it is forbidden.

הלכה טז
גֶּפֶן שֶׁיָּבְשׁוּ הֶעָלִין שֶׁלָּהּ וְנָפְלוּ כְּדֶרֶךְ שֶׁתִּיבַשׁ הַגֶּפֶן בִּימֵי הַקֹּר אָסוּר לִזְרֹעַ בְּצִדָּהּ יָרָק אוֹ תְּבוּאָה וְאִם זָרַע לֹא קָדְשׁוּ. וְכֵן הַזּוֹרֵעַ בְּעָצִיץ שֶׁאֵינוֹ נָקוּב הַמֻּנָּח בַּכֶּרֶם לֹא קִדֵּשׁ וּמַכִּין אוֹתוֹ מַכַּת מַרְדּוּת. אֲבָל עָצִיץ נָקוּב הֲרֵי הוּא כְּאֶרֶץ:
כסף משנה
16.
When a vine has dried out and its leaves have fallen as is frequent in the winter,45In his Commentary to the Mishnah (Kilayim 7:2), the Rambam emphasizes that we are speaking about a vine that is alive and will produce grapes in the future and not one that has dried out entirely. If the vine is totally dried out, it is permissible to sow other species near it (Radbaz, Kessef Mishneh, commenting on the gloss of the Ra'avad). it is forbidden to sow vegetables or grain next to it. If one sows them there, they do not become hallowed. Similarly, if one sows these species in a flowerpot that does not have a hole which is located in a vineyard, the produce is not hallowed.46As indicated by Chapter 1, Halachah 2, this reflects a general principle applicable in many contexts of agricultural law: If a flowerpot has a hole at its bottom, it is considered as being a part of the field, because it derives nurture there. If it does not have such a hole, it is considered as a separate entity. He, however, should be given stripes for rebellious conduct.47The punishment administered for the violation of a Rabbinic commandment. If, however, the flowerpot has a hole, it is [as if he sowed] in the ground.48For it derives nurture from the ground through the hole. See the Rambam's Commentary to the Mishnah (Demai 5:10).

הלכה יז
הָיָה עוֹבֵר בַּכֶּרֶם וְנָפְלוּ מִמֶּנּוּ זְרָעִים אוֹ שֶׁיָּצְאוּ עִם הַזְּבָלִים אוֹ עִם הַמַּיִם אוֹ שֶׁהָיָה זוֹרֵעַ אוֹ זוֹרֶה בְּשָׂדֶה לָבָן וּסְעָרַתּוּ הָרוּחַ לַאֲחוֹרָיו וְנָפְלוּ הַזְּרָעִים בַּכֶּרֶם וְצָמְחוּ הֲרֵי זֶה לֹא נִתְקַדֵּשׁ שֶׁנֶּאֱמַר (דברים כב ט) "אֲשֶׁר תִזְרַע" וְזֶה לֹא זָרַע. וְחַיָּב לַעֲקֹר כְּשֶׁיִּרְאֶה. וְאִם קִיְּמָן הֲרֵי זֶה קִדֵּשׁ. סְעָרַתּוּ הָרוּחַ לְפָנָיו וְרוֹאֶה הַזְּרָעִים שֶׁנָּפְלוּ לַכֶּרֶם הֲרֵי זֶה כְּזוֹרֵעַ. וְכֵיצַד יַעֲשֶׂה. אִם צָמְחוּ הָעֲשָׂבִים יַהַפְכֵם בְּמַחְרֵשָׁה וְדַיּוֹ. וְאִם מְצָאָן שֶׁנַּעֲשׂוּ אָבִיב יְנַפֵּץ אוֹתוֹ אָבִיב כְּדֵי לְהַשְׁחִיתוֹ שֶׁהַכּל אָסוּר בַּהֲנָאָה. וְאִם מְצָאָהּ שֶׁנַּעֲשֵׂית דָּגָן הֲרֵי זוֹ תִּשָּׂרֵף. וְאִם רָאָה אוֹתָן וְקִיְּמָן הֲרֵי אֵלּוּ יִשָּׂרְפוּ עִם הַגְּפָנִים הַסְּמוּכוֹת לָהֶן:
כסף משנה
17.
[The following rules apply when a person] was passing through a vineyard and seeds fell from him49Without his knowledge. or they were brought [into a field] with fertilizer or water, or one was sowing or winnowing in a field of grain and the wind carried the seeds behind him and the seeds fell into a vineyard and sprouted, they do not become hallowed. [This is derived from the prooftext cited above] which states "which you sowed," and this was not sowed.50On the contrary, they fell in the vineyard against his will [ibid. (Kilayim 5:7)]. He is, [nevertheless,] obligated to uproot it when he sees it. If he maintains it, it becomes hallowed.51For whenever mixed species are maintained in a vineyard, they become hallowed, as stated in Halachah 8.
If the wind carried the seeds before him and he saw them fall into the vineyard, he is considered to have sown them. What should he do if their grasses grow? He should turn them over with a plow; this is sufficient. If he discovered that they have already ripened,52But had not seen them beforehand. he should crush the portion that ripened,53Although generally, kilayim should be destroyed by fire, an exception is made in this instance, because - since the newly grown crops are moist and not appropriate to be burnt. for it is forbidden to benefit from the entire54I.e., even its straw (Radbaz, Kessef Mishneh; this ruling appears to contradict the Rambam's Commentary to the Mishnah (loc. cit.). [plant].55The grain is forbidden from the time it becomes rooted in the ground. The vines are not forbidden unless they grow 1/200th of their size. Alternatively, since he did not purposely plant the grain, even if the vines grew that much, they are not forbidden as long as the person did not willfully maintain the mixed species (Radbaz). If he discovers that grain has already sprouted,56For whenever mixed species are maintained in a vineyard, they become hallowed, as stated in Halachah 8. it must be burnt. If he saw it and maintained it, it must be burnt together with the vines adjacent to it.

הלכה יח
הָרוֹאֶה בַּכֶּרֶם עֵשֶׂב שֶׁאֵין דֶּרֶךְ בְּנֵי אָדָם לְזָרְעוֹ אַף עַל פִּי שֶׁהוּא רוֹצֶה בְּקִיּוּמוֹ לִבְהֵמָה אוֹ לִרְפוּאָה הֲרֵי זֶה לֹא קִדֵּשׁ. עַד שֶׁיְּקַיֵּם דָּבָר שֶׁכָּמוֹהוּ מְקַיְּמִין רֹב הָעָם בְּאוֹתוֹ מָקוֹם. כֵּיצַד. הַמְקַיֵּם קוֹצִים בַּכֶּרֶם בַּעֲרָב שֶׁרוֹצִים בַּקּוֹצִים לִגְמַלֵּיהֶם הֲרֵי זֶה קִדֵּשׁ:
כסף משנה
18.
When a person sees an herb that [most] people would not plant [growing] in a vineyard, it does not become hallowed57In his Commentary to the Mishnah (Kilayim 5:8), the Rambam explains that this is also derived from the prooftext cited above. "Which you sowed" implies "what is customary for you to sow." even though he desires that it be maintained [so that he will use it] for animal [fodder]58Compare to Chapter 1, Halachah 4. or for medicinal purposes unless most people in that locale59I.e., everything depends on the prevailing local practice. What the person thinks individually is not of consequence. would maintain such a plant. What is implied? [When] a person maintains brush [growing] in his vineyard in Arabia, it becomes hallowed, [because there most people] desire the brush for their camels.

הלכה יט
הָאִרוּס וְהַקִּיסוֹס וְשׁוֹשַׁנַּת הַמֶּלֶךְ וּשְׁאָר מִינֵי זְרָעִים אֵינָן כִּלְאַיִם בַּכֶּרֶם. הַקַּנְבּוֹס וְהַקִּנְרָס וְצֶמֶר גֶּפֶן הֲרֵי הֵן כִּשְׁאָר מִינֵי יְרָקוֹת וּמְקַדְּשִׁים בַּכֶּרֶם. וְכֵן כָּל מִינֵי דְּשָׁאִים שֶׁעוֹלִין מֵאֲלֵיהֶן בַּשָּׂדֶה הֲרֵי הֵן מְקַדְּשִׁין בַּכֶּרֶם. וּפוֹל הַמִּצְרִי מִין זְרָעִים הוּא וְאֵינוֹ מְקַדֵּשׁ. הַקָּנִים וְהַוֶּרֶד וְהָאַטָּדִין מִינֵי אִילָן הֵן וְאֵינָן כִּלְאַיִם בַּכֶּרֶם:
כסף משנה
19.
Mint, ivy, the king's lily, and other [similar] plants are not considered as kilayim in a vineyard. Hemp, artichokes,60Our translation is taken from Rav Kappach's notes to the Rambam's Commentary to the Mishnah (Uktzin 1:6). and cotton, are considered like other types of vegetables and they become hallowed in a vineyard. Similarly, all types of herbs that grow on their own accord in a field become hallowed in a vineyard. An Egyptian bean is considered as a plant and does not become hallowed. Bamboo, roses, and thornbushes are considered as species of trees and are not kilayim in a vineyard.61As stated in Halachah 6, all types of trees may be planted in a vineyard.

הלכה כ
זֶה הַכְּלָל כָּל הַמּוֹצִיא עָלִין מֵעִקָּרוֹ הֲרֵי זֶה יָרָק וְכָל שֶׁאֵינוֹ מוֹצִיא עָלִין הֲרֵי זֶה אִילָן. וְהַצָּלָף אִילָן לְכָל דָּבָר:
כסף משנה
20.
This is the general principle: Whenever the leaves of a plant grow from its roots, it is considered a vegetable.62In such an instance, each year, the trunk changes. If its leaves do not grow from its roots, it is not a vegetable. A caper tree is considered as a tree in all contexts.63Compare to Hilchot Ma'aser Sheni 1:7. See also Hilchot Berachot 8:6.

הלכה כא
הָרוֹאֶה יָרָק בַּכֶּרֶם וְאָמַר כְּשֶׁאַגִּיעַ לוֹ אֶלְקְטֵנוּ מֻתָּר. הִגִּיעַ לוֹ וְעָבַר מֵעָלָיו וְאָמַר כְּשֶׁאֶחֱזֹר לוֹ אֶלְקְטֵנוּ אִם שָׁהָה עַד שֶׁהוֹסִיף אֶחָד מִמָּאתַיִם הֲרֵי זֶה קִדֵּשׁ:
כסף משנה
21.
When a person sees a vegetable [growing] in [his] vineyard and says: "When I reach it, I will take it out," it is permitted.64I.e., he need not hurry to uproot it immediately, but may proceed at his ordinary pace, provided he does not delay. Should he reach it and pass it by, saying: "When I return, I will take it out,"65He has transgressed, because he has maintained mixed produce in a vineyard. if he waits [the time it takes] to add 1/200th [to its size], it becomes hallowed.

הלכה כב
וְכֵיצַד מְשַׁעֲרִין שִׁעוּר זֶה. רוֹאִין אִם נֶחְתַּךְ יָרָק זֶה אוֹ מִין תְּבוּאָה זֶה מִן הָאָרֶץ בְּכַמָּה זְמַן יִיבַשׁ. הַגַּע בְּעַצְמְךָ שֶׁיִּיבַשׁ עַד שֶׁלֹּא תִּשָּׁאֵר בּוֹ לֵחָה בְּמֵאָה שָׁעָה. אִם נִשְׁתַּהָה בָּאָרֶץ מִשֶּׁהִגִּיעַ לוֹ חֲצִי שָׁעָה הֲרֵי הוֹסִיף בְּמָאתַיִם לֶאֱסוֹר. וְאִם שָׁהָה פָּחוֹת מֵחֲצִי שָׁעָה מֻתָּר:
כסף משנה
22.
How can we measure this degree [of growth]? We see how long it would take for this vegetable or grain to dry if its connection with the earth were severed.66As the Jerusalem Talmud (Kilayim 5:6) explains, a plant will grow at the same rate that it will dry out. (As the Radbaz points out, this applies over the entire span. The particular phases of its growth and drying will vary.) Let us say that it would take 100 hours to dry to the point that it retained no moisture. Thus if it remained in the ground for half an hour after he reached it, it will have added 1/200th [to its size] and it is forbidden. If he waited less than half an hour, it is permitted.

הלכה כג
אָסוּר לַעֲבֹר בְּעָצִיץ נָקוּב שֶׁזָּרוּעַ בּוֹ יָרָק בְּתוֹךְ הַכֶּרֶם. וְאִם הִנִּיחוֹ תַּחַת הַגֶּפֶן וְנִשְׁתַּהָה שָׁם בָּאָרֶץ כְּדֵי לְהוֹסִיף אֶחָד מִמָּאתַיִם הֲרֵי זֶה קִדֵּשׁ:
כסף משנה
23.
It is forbidden to carry a pot with a hole [at its bottom]67As stated in the notes to Halachah 16, when such a flowerpot is left on the ground, it is considered as if the pot is connected to the earth and it as if the plants growing in it are part of the vineyard. As a safeguard, our Rabbis forbade even carrying such a flowerpot through a vineyard. in which a vegetable is growing through a vineyard.68According to the Rambam, however, the produce growing in it does not become hallowed. If one left [such a pot] under a vine on the earth for [the time it takes] to add 1/200th [to its size], it becomes hallowed.

הלכה כד
בָּצָל שֶׁנְּטָעוֹ בַּכֶּרֶם וְאַחַר כָּךְ נֶעֱקַר הַכֶּרֶם וְאַחַר כָּךְ צָמְחוּ בְּצָלִים מִן הָעִקָּר הַנָּטוּעַ אַף עַל פִּי שֶׁרַבּוּ הַגִּדּוּלִים עַל עִקָּרוֹ בְּמָאתַיִם הֲרֵי אוֹתוֹ הָעִקָּר בְּאִסּוּרוֹ שֶׁאֵין גִּדּוּלֵי הֶתֵּר מַעֲלִין אֶת הָעִקָּר הָאָסוּר:
כסף משנה
24.
[The following law applies when one] sowed an onion in a vineyard,69And thus it became forbidden as kilayim. the vineyard was uprooted afterwards,70But the forbidden onion plant was left in the ground. and then the onions grew from the roots that were already planted. Even though the growths are more than 200 times the size of the root,71And mixed species are nullified in a mixture 200 times the size of the original amount. the root remains forbidden, for the permitted growths cannot change the status of the forbidden root.72Instead, despite the growth of the onion plant, the root remains forbidden. Rabbi Akiva Eiger notes that the Rambam rules in this manner in Hilchot Neta Reva'i 10:16. In Hilchot Terumah 11:22, he rules otherwise.
The Rambam's wording could be interpreted as implying that the plant that grows from the root is permitted. This is the conclusion of Rav Yosef Corcus. There are other Rishonim who maintain that the entire plant is forbidden. Kin'at Eliyahu notes that in Hilchot Nedarim 5:15, the Rambam rules: "If it was an entity whose seed does not decompose, even the produce that grows from the produce that grows from them is forbidden." Seemingly, the same principles would apply here.

זרעים הלכות כלאים פרק ה
Zeraim Kilayim Chapter 5