Cultivation:  Plant ¼-inch deep, indoors, six to eight weeks prior to last frost. After hardening off, transplant into deeply cultivated, well-drained beds into which generous amounts of organic matter and composted manure have been added. Final spacing should be eighteen to twenty four inches.

Rhubarb is a cool season crop that requires temperatures below 40°F to break dormancy and to stimulate good spring growth.  For growth to remain vigorous, summer temperatures should average less than 75°F. This means that the Northern U.S. and Canada are best suited for rhubarb production.

It is best to wait until the second year before harvesting stalks and even then, be conservative. Pull the stalks instead of cutting. Remove flower stalks as soon as you see them.  You will not get full harvests until the third year. Rhubarb plantings will be productive for fifteen years or longer.

General poisoning notes for rhubarb

The plant contains oxalate crystals, which have been reported to cause poisoning when large quantities of raw or cooked leaves are ingested. Anthraquinones (glycosides) have been implicated more recently in the poisoning. The stalks are widely used as preserves and are also eaten raw, without problems. The toxic content is much lower in the stalks. Humans have been poisoned after ingesting the leaves. Human poisoning was a particular problem in World War I, when the leaves were recommended as a food source in Britain. Some animals, including goats and swine, have also been poisoned by ingesting the leaves. Children should be taught to eat only the rhubarb stalks, preferably under supervision (Robb 1919; Cooper and Johnson 1984).

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Robb, H. F. 1919. Death from rhubarb leaves due to oxalic acid poisoning. J. Am. Med. Assoc., 73: 627-628.