Will That Plant Grow Here?
Plants growing in a specific area are determined by the average high and low temperatures as well as the amount of moisture. People transplanted to our zone 8 climate are frequently surprised by the different types of plants and how differently the plants they bring with them perform. Rhubarb is one of those plants commonly grown in zones 6 and cooler zones. Some gardeners are asking: Will rhubarb successfully grow here?
Rhubarb looks like an impressive exotic tropical plant but it prefers a cool climate. The plant produces long crimson or light green stalks topped with large ruffled green leaves. The extremely tart stalks are the only edible part of the plant as the leaves contain high levels of oxalic acid. It grows best in zones where the ground freezes in winter. You can find rhubarb growing in the field from Maine to Washington state. Plants require an extended chilling period with temperatures below 40 degrees to produce a crop of stems. Why would anyone in the south want to grow rhubarb where the environment is not ideal?
Rhubarb stalks are a low-calorie, low-starch, high-fiber vegetable providing a good source of magnesium, vitamins C and K, calcium and manganese. Leaves are removed and discarded at harvest and the stalks are usually prepared like a fruit and commonly mixed with other fruits in pies, crisps, jams, muffins, and quick breads. The flavor is memorable and worth the effort to grow in our warm environment.
It can be tricky to grow rhubarb here so remember these tips. Choose a location that will shelter the plant from extreme summer heat. Afternoon shade in the summer is necessary. Look for a location on the north side of a grape arbor or under the shade of a deciduous tree. Rhubarb plants prefer a well-drained soil and plenty of room as they can grow to 36 inches. It is a heavy feeder and will grow better if the soil in the planting hole is well prepared. Dig to a depth of at least one foot and work in organic matter, compost or manure. Plant crowns only 4 inches deep. Water newly planted crowns and make sure to keep the soil moist during the growing season. To reduce summer heat, mulch plants with two inches of organic material like compost, or shredded bark.
Plan to begin harvest during the second or third season of growth with just a few stalks. Two harvest times are recommended: one is early summer and the second in late fall. Harvest by cutting the stalk at the base of the plant or pulling and twisting the stalks at the soil line. The older the plant the more stalks it will grow and the more you can harvest. When the plant produces 10 stalks you can harvest 3 or 4. Do not cut more than one-third of the stalks during any harvest to have continued production.
Rhubarb plants may die down to the ground in the fall with new growth appearing in early spring. Some prefer to grow it as an annual and replant every spring. If you enjoy eating rhubarb, now is a good time to start a plant to enjoy.