Hemp is used for a variety of purposes, the fibers are used in clothing, the fresh leaves can be consumed as salad, hemp seeds are eaten by birds and humans, and you can produce marijuana or hashish from the leaves and flowers. For the kitniot discussion, only the seeds are relevant.
Do hemp seeds look like kitniot? Not really in my opinion. Is hemp grown with grains? I don’t know. Can the products (hemp seed oil or hemp cookies) be confused with chametz products? Oil never, the cookies also not really in my opinion. So, last resort, are hemp seeds in the category of kitniot for forbidden mixtures of seeds? The Rambam says "Hemp, artichokes, and cotton, are considered like other types of vegetables" (Mishne Tora, Hilchot Kilayim 5:19). Seems to me like a pretty clear non-kitniot. The lists seems to be divided on the issue: OU and Star-k do not list hemp. Kashrut.com lists hemp seeds and the cRc Guide lists just ‘hemp’.
I would stick with hemp seeds as non-kitniot, but for the sake of discussion let’s assume it is kitniot. So now to the interesting question: Can I have a joint on pesach?
First of all, we need to ask, is pot kosher at all? Some rabbis say no, e.g., Rabbi Moshe Feinstein (Shu”t Iggerot Moshe, Y”D vol. 3, no. 35) and Rabbi Shlomo Zalman Auerbach (Nishmat Avraham, O”H no. 155, no. 4). You can probably find other rabbis that say yes (this comment by Yoreh K’chetz on January 24, 2011 at 7:19 am offers some arguments or ask Aleh Yarok).
Second, marihuana would only be a problem if it contains hemp seeds. As far as I am informed, weed is produced from flowers and leaves, only the low-quality products contain seeds. So you should be fine if you buy high-quality stuff.
Third, you are allowed to benefit from kitniot, only eating is not allowed. Is smoking eating? Rabbi Ya’akov Emden seems to think that smoking is merely deriving benefit and would allow even cigarettes soaked in beer on Pessach (Mor u-Kitziya no. 511, found in Dan Rabinowitz: Kitniyot and Stimulants: Coffee and Marijuana on Passover).
Finally, just for fun, a link to two news articles that deal with the topic: Is marijuana kosher for Pessah? (JPost) and Is pot kosher for Pesach? (JTA). Note the lack of understanding the halachot of kitniot from nearly all partners (including Aleh Yarok and the couple interviewed in JPost). It is only hemp seeds that are kitniot, there is no need to ban "everything containing hemp". You do not need to sell kitniot or get rid of it in any way, you may keep it in your home. And certainly you do not have to clean again because of kitniot.
As a conclusion: Hemp seeds are not kitniot and the whole thing is probably just an attempt by Aleh Yarok to get into the media. Btw: Say no to drugs and smoking may be hazardous to your health.
- Danger of chametz traces: Don’t know.
- Danger of confusion with chametz (raw): No.
- Danger of confusion with chametz (processed): Oil no, cookies not really.
- Botanical categorization:Cannabaceae (flowers).
- Known in 13th century: Yes.
- Verdict: Not kitniot.
photo (c) D-Kuru/Wikimedia Commons