Native to Asia and Europe and grown in both temperate and subtropical climates, this perennial plant has long stalks and large leaves called petioles. Rhubarb requires a cold season to flourish; it likes a winter where the temperatures go to at least 40 degrees or below (it needs this to break dormancy), making it an ideal choice for northern climates. Once temperatures reach between 75 to 80 degrees, plant growth slows down. Gardeners living in southern climes have had some success growing it as an annual, planting it in early spring.
Rhubarb is best started from root divisions or by cutting crowns and dividing them, making sure that each division has a piece of crown, or bud and root enough to grow. You can get these from nurseries or catalogues, or from friends who are dividing their rhubarb plants. Plant the roots in early spring in fertile, well-drained soil that is enriched with organic matter like compost and aged manure; it does best with a pH between 6 and 6.5. Rhubarb will do best in full sun, however, it can grow in some partial shade, but plants and yield will be smaller. Some gardeners plant in hills and others in rows; plant about 3 to 4 feet apart and cover the roots so that the buds or crowns are covered with about 2 inches of soil. It is important to water well for the first few months, especially if it is dry. Straw or leaf mulch is a good idea to retain moisture and discourage weed growth.
It is important to keep rhubarb free of weeds and to keep the seed stalks cut back. Once it produces seed stalks, growth and production of petioles slows down. The first year plants should be harvested sparingly; thereafter, the entire plant can be harvested. Stalks can be harvested by pulling them out from the base one at a time or cutting them at soil level with a sharp knife. The entire plant can be harvested all at once or anytime during its growing season as needed. Depending on the individual plants and the climate, harvest season starts in May or June sometimes there will be a second harvest in August. After the first harvest, or when the plants start putting out small and thin petioles, it is time to stop harvesting and give the plants a rest. If watered during the hotter weather, plants may produce again during the cooler weather of September or October. This depends totally on type of plant and where and how they are grown.Much of the rhubarb we buy at market is field grown, however, there is also quite a bit of hothouse-grown rhubarb. Crowns are moved into hothouses so that they can be forced during the winter months. Some say that hothouse-grown rhubarb is milder; I am not sure I agree. Rhubarb cultivars are plentiful – they come in green, pink and red, some with 10-inch-long petioles, while others reach 18 inches. Red does not necessarily mean more mature or better flavor; pink and green are just as delicious. And bigger does not always mean better; sometimes the smaller stalks are more tender. In season, choose fresh, firm stalks that are glossy and aren’t limp and ones that are free of brown spots.