Rhubarb is propagated from crowns, or segments, of the parent plant, available at nurseries in spring. Choose crowns that are firm, free of rot and have one or more round, reddish buds. Three to five plants provide ample fresh and frozen rhubarb for a family of four. Spring planting is best across the country, except for coastal British Columbia, where fall planting is fine. Here are some tips to get plants off to a good start—and keep them healthy and productive for many years.
Planting and rhubarb care
Plant in full sun in fertile, well-drained, slightly acidic soil. Plants can grow more than three feet (90 centimetres) tall with a spread of four to five feet (120 to 150 centimetres)—take this into account when deciding where to place them.
- Dig a hole 11 inches to two feet (45 to 60 centimetres) deep and two feet in diameter.
- Add six inches (15 centimetres) of compost or well-rotted manure.
- Fill with a mixture of soil and compost, leaving a depression for the crown.
- Set the crown in the hole, and cover the buds with one inch (2.5 centimetres) of soil.
- Water well; mulch with a mixture of compost and straw, hay or shredded leaves to a depth of six inches (15 centimetres), leaving a space in the centre so the crown is uncovered.
- Keep the soil moist but not soggy.
- Feed midsummer with a layer of compost around the crowns, or a granular organic fertilizer. If your soil is poor, feed every two or three weeks with compost tea (made by soaking a bag of compost in a pail of water overnight).
- Remove flower stalks as they appear. In fall, remove dead leaves, fluff up the mulch and lay an inch of new mulch over the crown; use six to eight inches (15 to 20 centimetres) in extremely cold climates.
- In spring, draw back the mulch, dig in compost or well-rotted manure and granular organic fertilizer, and replace the mulch, avoiding the crown.
- Don't harvest stalks the first year, plants need to devote their energy to developing a good root system. During the second year, harvest only a few stalks during the first two weeks of the season. In subsequent years, harvesting can continue for eight to 10 weeks.
- Rhubarb leaves can be composted but should never be eaten—they contain high amounts of oxalic acid.
- To prevent disease, keep your garden well weeded and do a good fall clean-up. Remove leaves that wilt, turn yellow or have watery spots on them. If the entire plant shows signs of wilting or disease, remove and destroy. Plant new crowns in another location.
Choose stalks that are at least a foot (30 centimetres) long. Grasp the stalk in your hand, slide your thumb down the inner groove as far as it will go, then twist the stalk while pulling up. Take fewer than half the stalks per plant in each picking.
After five to 10 years—earlier if the plant starts producing small, tough stalks instead of large, juicy ones—the crown needs dividing. Divide in early spring before the shoots emerge. Dig up the crown and cut off large side roots. Using a spade, divide the crown into pieces, making sure each piece has roots and at least two buds. Replant as you would a new crown.