Kilayim, Chapter Three, Mishnah Seven
This mishnah deals with how close one may sow gourds to other species of vegetables or grain.
1) A gourd [sown] among a [different] vegetable [must be separated by as much] as any other vegetable.
2) [A gourd sown] among grainhe must give it [a separating space of] a bet rova.
3) If his field was sown with grain, and he wishes to plant within it a row of gourds, he must give [the gourds] six handbreadths for them to be worked.
a) And if [the row of gourds] overgrows [into the border] he must pull up that which is within it.
4) Rabbi Yose says: he must give [the gourds] four cubits for them to be worked.
a) They said to him: Do you rule more stringently with regard to this than with regard to a vine?
b) He said to them: We find that [the gourd] is treated more stringently than a vine, since for a single vine he must give six handbreadths for it to be worked, but for a single gourd a bet rova.
5) Rabbi Meir said in the name of Rabbi Ishmael: if there are as many as three gourds in a bet seah, he may not bring [another] seed into the bet seah.
a) Rabbi Yose ben Hahotef Ephrati said in the name of Rabbi Ishmael: if there are as many as three gourds in a bet kor, one may not bring [another] seed into the bet kor.
Section one: If he wants to sow a single gourd plant next to a different vegetable, the same rule that always applies to vegetables still applieshe must distance them six handbreadths.
Section two: However, if he wants to sow the gourd next to grain, he must separate them the same distance that grains must be separatedby a bet-rova (a space big enough to grow a quarter kav of grain). This is 10.2 cubits by 10.2 cubits, or about 25 square meters (see above 2:10).
Section three: If he wants to make an entire row of gourds he need not separate it as far from the grain as he would if it were a single plant, because an entire row is recognizable as being distinct and looks less like kilayim than does a single plant. All he must do is separate the row of gourds from the grain by six handbreadths, the amount of space he needs around the gourds in order to take care of them. If the gourd plants overgrow this six handbreadth limit, he needs to remove the leaves that creep into the separation area.
Section four: Rabbi Yose disagrees with the previous opinion and holds that he must give the gourds four cubits space to work them.
The other rabbis respond that this would make the rule with regard to gourds stricter than the rule with regard to vines. Below in mishnah 4:5 we will learn that when it comes to separating vines from grain, only six handbreadths are required. Since the rules of kilayim governing vines mixed in with grain are in some ways stricter than those governing mixing of seeds, the rabbis question why Rabbi Yose is stricter with regard to the mixing of seeds.
Rabbi Yose answers that there is precedent for his strict ruling. Single vines may be planted six handbreadths from grain, whereas single gourd plants must be distanced by a bet rova, as we learned above. In essence, Rabbi Yose holds that there is no difference in the distancing of single plants from full rowsif a single plant must be distanced by a bet-rova, then so too must the full row.
Section five: Rabbi Meir says that if there are three gourd plants in a field the size of a bet seah (2500 square cubits) then he should not put any other type of seed in that plant. From here we can see that according to Rabbi Meir, gourds must be separated from other vegetables by the distance of 1/3 of a bet seah, and not merely by a bet rova, a far smaller amount. Rabbi Meir attributes this opinion to Rabbi Ishmael.
Rabbi Yose ben Hahotef Ephrati transmits an even stricter opinion in the name of Rabbi Ishmael. A bet kor is 75,000 square cubits. If one brings so much as three gourd plants into a field this size, he may not plant another species of vegetable in that same field.