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One of spring's garden harbingers, rhubarb stems burst through soil early in the growing season. The tart, colorful stems grace pies and jams with tangy flavor that is typically tamed with sugar or teamed with sweet strawberries.
Rhubarb adds sculptural beauty to the garden with its blocky stems and large leaves. While leaves offer textural beauty, they're not part of the harvest package. Rhubarb leaves contain high concentrations of oxalic acid and shouldn't be eaten. When growing rhubarb, harvest the stems, then remove leaves and add them to the compost pile. Rhubarb grows best in zones where the ground freezes in winter. Plants require an extended chilling period with temperatures below 40 degrees to produce a crop of stems. As a result, rhubarb is commonplace in gardens throughout the coldest sections of the country, although it can be grown as far south as zone 7.
Quick Answers
- When can I start harvesting rhubarb? Harvest lightly in year 2, then harvest regularly starting in year 3.
- How do I know rhubarb is ready to pick? Look for reddish stalks about 12 to 18 inches long.
- Can I harvest rhubarb all summer? You can harvest into summer, but stop when stalks get short and thin.
- Are rhubarb leaves edible? No—harvest the stalks only and compost the leaves.
Quick Guide to Growing Rhubarb
- Plant rhubarb during the cool days of early spring, once the ground thaws.
- Rhubarb produces a harvest for up to 8 years, so grow it in a sunny area where it will go undisturbed for a long time.
- Give rhubarb room to spread out by planting them 4 to 6 feet apart.
- Improve your native soil by mixing in several inches of aged compost or other rich organic matter.
- When hot weather arrives, apply a 2-inch layer of mulch to keep soil moist and help block weeds.
- Check soil moisture regularly and water when the top inch of soil becomes dry.
- Feed rhubarb regularly with a continuous-release plant food.
- Start regular harvesting in year 3 when stalks are 12 to 18 inches long and reach their ideal red color.
Soil, Planting, and Care
A true perennial, rhubarb plants can yield harvests 5 to 8 years or longer. Once plants are established, they don't transplant easily, so choose your planting site carefully. It will also help to start with the best plants you can get. Young Bonnie Plants® rhubarb plants are strong and vigorous, so you're already ahead of the game when you plant. Rhubarb thrives in full sun but will yield to light shade. Select a location that gives plants ample room; individual rhubarb plants can measure up to four feet wide and tall.
Plant crowns in spring as soon as soil is workable. Tuck plants into slightly acidic soil rich in organic matter; blend in plenty of well-rotted manure or compost, or improve the soil with aged compost-enriched Miracle-Gro Organic™ Garden Soil. Rhubarb crowns require shallow planting (around 4 inches deep), but because plants are such heavy feeders, you should dig planting holes at least a foot deep. If your soil is heavy clay, you may want to consider planting rhubarb in raised beds filled with soil designed especially for that kind of growing environment, such as Miracle-Gro Organic™ Raised Bed & Garden Soil.
Water newly planted crowns, and keep soil moist throughout the growing season. As summer heat arrives, mulch plants with a 2-inch-thick layer of organic mulch, such as compost, straw, or shredded bark. Replenish mulch throughout the growing season as needed to maintain 2-inch thickness. Best growth comes from using plant food that works in concert with the soil to provide just the right nutrition for your rhubarb plants. Miracle-Gro Organic™ Liquid Plant Food feeds plants quickly while also supporting beneficial soil microbes.
In fall, when stems die back, remove all plant debris. Mulch plants after the ground freezes, covering crowns with 2 to 4 inches of compost or leaves.
Troubleshooting
Established plants need to be divided every 5 to 10 years. You'll know it's time to divide when stems are crowded and thin. Divide when plants are dormant, in early spring or fall. Dig and lift clumps, cutting roots into pieces about 2 inches across. Take care not to damage the buds on the top of each root section. Replant the best sections.
Few problems plague rhubarb. Crown rot settles in when soil drainage is poor. This disease damages terminal buds, which results in spindly, weak stems. The cure is to dig out and destroy infected plants. Don't replant rhubarb in areas where crown rot has damaged plants before.
Leaf spots can attack the plant, with the worst being red leaf, or Ramularia, which can ruin the stems. Cut away old foliage in fall to help prevent leaf spot, whose spores overwinter in the debris.
Rhubarb curculio occasionally attacks plants. Insects puncture leaf stalks from late spring to early summer as they feed and lay eggs. Damaged stems ooze sap and may begin to decay.
Harvest and Storage
Forget harvesting the year that you add rhubarb to the garden. In the second year after planting, harvest lightly, removing only a few stalks from each plant. From the third year on, harvest stems freely. To ensure continued production, take care not to remove more than one-third to one-half the stalks from any one plant during any one harvest.
To harvest, choose stems that are 12 to 18 inches long and reddish in color. Grasp the stalk near the base and pull it upwards, twisting the stem as you pull. You can also use a sharp knife to slice stems from the plant. Cut as close to the crown as possible without damaging it. After harvesting, remove the leafy portion and the base of the stem, leaving only the colored stalk.
Early spring stems offer the most flavor and tenderness; they're ideal for pies. Stems harvested later in the season tend to be tougher, so reserve them for stewing, sauces, or jams.
Stop harvesting as stems get shorter and thinner. At this point, plants are storing up energy for next year's harvest. Mature plants typically provide an 8- to 10-week harvest. In general, expect 2 to 3 pounds of stalks per mature plant per season.
For the best quality in cooking or freezing, use freshly harvested stalks. If that is not possible, keep cut stems up to 1 week in the refrigerator, although crispness diminishes with storage. You can refresh crispness by standing stored stems in water before using; however, the flavor will be slightly diluted. You can also chop stems and freeze the pieces in a plastic freezer bag for much later use.
FAQs
When can I start picking rhubarb after planting?
Don’t harvest rhubarb the first year after planting. Give plants time to build a sturdy root system.
In year 2, harvest lightly (just a few stalks per plant). Starting in year 3, you can harvest more freely.
What are the white stalks rising from the center of my rhubarb plant?
Those are flower stalks. Remove them as soon as they appear.
Blooming uses energy that would otherwise support root strength and next season’s stalk production.
How do I know when rhubarb is ready to pick?
Harvest when stalks are about 12 to 18 inches long and reddish in color.
Smaller-diameter stalks are usually the most tender. Thick stalks can become pithy or tough later in summer, especially during drought.
How do I harvest rhubarb?
Pull stalks from the base with a gentle twist, or cut them cleanly near the crown.
Avoid injuring the central bud. At each harvest, take no more than about one-third of the stalks from a plant.
Can I harvest rhubarb stems all summer?
You can harvest into summer, as long as plants aren’t flowering and stalks remain strong.
Stop harvesting when stalks become small and short—at that point, the plant is storing energy for next year. Keep plants watered until frost.
My rhubarb stalks are falling over and rotting. What’s happening?
This is often a sign of crown rot, which is encouraged by poor drainage.
Remove and destroy affected plants. Don’t replant rhubarb in the same spot. To help prevent crown rot, grow rhubarb in well-drained soil, use raised beds when needed, and divide crowded clumps.
Can I divide an overgrown rhubarb patch, and when should I do it?
Yes—divide rhubarb in early spring before growth begins.
Slice off a section with a sharp spade and lift as much root as possible. Each division should have at least two buds. Plant buds about 1 inch below the soil surface, and if possible, leave part of the original crown undisturbed so it can continue producing.
