Your rhubarb is ready for harvest when the stalks are anywhere from 7 to 15 inches long and once the leaves have fully opened. Don’t look at the stem colour for an indication of ripeness as they can be varying levels of red or even green depending on the variety.
When properly harvested, rhubarb is likely to live and give you plenty of good stalks for 10 or more years. After your rhubarb plant has established itself, you will want to harvest rhubarb every year to prevent overcrowding.
To harvest, find a stalk that is ready to go. Solidly grasp the stem near the base of the plant, twist to the side, and pull to remove. The stalk should pop right off and come away from the root cleanly.