These are potted up root divisions from the robust healthy plants we have here at the farm.
 
These fast-growing perennials are hardy from Zones 3 - 8 , can be planted 2-3 ft apart and will grow 2-3 ft high.
 
Cut back their flower stalks to encourage more shoots, and also in their first year to help them focus on root growth. You can harvest stalks repeatedly until the new shoots erupting from the crowns begin thinning. Leave those later flushes to recharge the roots for ensuing years.
 
Divide roots every second or third year to keep them from overcrowding, and get more rhubarb plants in the process! Once established, their flowers can be left. They are a pretty white cluster of blossoms that shoot another couple feet above the stalks that attract pollinators. The seed is easy to collect from the dried flower stalks.