Safely Harvesting Rhubarb [Split from Home Cooking]
Just thought I'd mention here although it's a gardening concern too... If the Mods move it, so be it:
Folks are mentioning the toxicity of the leaves and that's something to be very careful of. The toxin is Oxalic Acid. . The plant is also poisonous to animals.
If you do plant them in the garden, do not cut the stalks off with a knife.... but rather Gently pull and twist at the point where the stalk meets the bottom of the plant. Snip off the leaf and dispose of it. Some people don't even compost it, but in a good hot compost heap the toxins are decomposed and harmless.
If stalks of seedheads appear just cut them a few inches from the bottom because if allowed to grow and flower they will diminish the quality of the stalks you want to eat.
for Pete's sake it is not so toxic it has to be treated gingerly. after you pull the rhubarb stalks, you can just break off the leaves and throw it in the compost. or even throw it down as mulch for the plant At any rate thats what my parents have been doing for 50+ years in their garden without ill effect. there is oxalic acid in a lot of food, spinach for example. Ive never noticed any animal chawing on the leaves either. Our cats and the animals that run thru parents garden certainly dont. Even if they tried it, they would probably find it unpalatable - they certainly wouldnt keel over dead after a little taste.
Your last advice is right on - even if it is ornamental you definitely want to remove the seedhead from rhubard if it appears - nip it in the bud - dont let it develop.
finally, not about harvesting, but the key to success with rhubarb is to give it adequate compost/food - it is a heavy feeder and your plants will not develop well except with rich soil.
My rhubarb isn't ready yet but I bought some at my greengrocer on the weekend and I was shocked to see them selling rhubarb stalks with the leaves. I know this. But I hope more people know this, too... Hope it isn't mis-interpreted for a rainbow chard which seems to be very popular these days.