Rhubarb grows best where the ground freezes in the winter. . Rhubarb requires an extended chilling period with temperatures below 40 degrees F to produce its stems. It is a common place vegetable throughout the colder parts of the United States. It may be grown as far south as zone seven, although that is unusual.
Rhubarb is a tart vegetable, so is mostly used in jams, jellies, and in pies. It is often paired with strawberries in pies to mitigate rhubarb’s tartness. Only the stems of the rhubarb plant are edible. The leaves contain oxalic acid and are poisonous.
This plant is a true perennial, and can be used in the landscape to show off its big leaves and blocky stems. As a perennial, it will spread in the garden, so grow it somewhere that can serve as a permanent home for it. Rhubarb may live five to eight years and occasionally longer.
To plant rhubarb, first till the ground to a depth of twelve inches. Place a three inch layer of compost over the tilled area. Till again to mix the compost with the soil. Dig a hole in the tilled area that is a foot deep. Fill the hole with loose soil and place the crown in four inches deep. The top of the crown should be level with the top of the soil. Water the crown in and add soil as necessary to keep it even with the ground around it.
Rhubarb needs to be kept moist during the growing season. Place a two inch layer of mulch around the plants to keep water in and heat out. Fertilize every couple of weeks during the growing season with a balanced fertilizer such as a 10-10-10.
In the fall when the vegetation falls, cut it back to the crown. After it freezes, mulch two to four inches over the crowns to protect them from the cold.
Every five to ten years, you will need to divide the rhubarb. It is time to divide it when the stems are crowded and thin. Divide when the rhubarb is dormant, in early spring or fall. Carefully dig the rhubarb up to divide it. Cut the root into two inch pieces taking care not to damage the root bud that produces the leaves. You should then replant the best pieces and discard the rest.
The rhubarb plant has few problems. Crown rot is the big one. It is caused by poor drainage in the bed where the rhubarb is growing. Dig out the effected plant and put it in the trash. Do not compost it as you will spread the disease. Do not replant rhubarb in areas where crown rot has been a problem.
Leaf spot can attack the plants, damaging the stems. Cutting off the foliage in the fall and discarding it helps prevent leaf spot.
Finally, the rhubarb curculio sometimes attacks the plants. These insects pierce the stem and suck the nutrients out of the plant. Damaged plants may ooze sap and begin to decay.