Fruits and Nuts » Small Fruits » Rhubarb 
Rhubarb leaves are poisonous.   If planting from seed, sow in early spring in rows 18 inches apart.  Transplant roots the second year to their permanent location, 3 to 4 feet apart.  16 plants are needed for the average family of four.  A packet of seed will produce about 20 roots, an ounce 100 roots.  If planting roots, set them out in early spring 3 to 4 feet apart each way in full sun.  Soil should be well-fertilized, light and airy.  Roots may be cut moderately the first year and regularly thereafter.  Does best in cooler climates.  Sorry, we cannot ship to AZ, CA and HI.