The 216th prohibition is that we are forbidden from planting grain or vegetables in a vineyard. This type of mixture is called kilai ha'kerem (kilayim in a vineyard).
The source of this commandment is G‑d's statement,1 "Do not plant your vineyard with kilayim."
In the words of the Sifri: "Why do we need the verse, 'Do not plant your vineyard with kilayim'? It already is written, 'Do not plant your field with kilayim,' which certainly includes both [kilayim in] a vineyard and a field!"
They answer, "This verse comes to teach that anyone who allows kilayim in a vineyard transgresses two prohibitions."2
You should be aware that kilai ha'kerem is prohibited by Torah law only in Eretz Yisrael. One who plants wheat, barley, and grapes in the same handful, and in Eretz Yisrael, is punished by lashes.
Outside Eretz Yisrael, this planting is forbidden by Rabbinic law and one who plants wheat, barley, and grapes in the same handful receives lashes by Rabbinic decree.
Grafting together trees [of different species], however, is [prohibited by Torah law and] punishable by lashes everywhere [‑both in Eretz Yisrael and outside Eretz Yisrael]. This prohibition is included in the general statement, "Do not plant your field with kilayim."3
The details of this mitzvah are also explained in tractate Kilayim.