Rhubarb (Rheum × hybridum)
Rhubarb (Rheum × hybridum) is a vital perennial vegetable known for tart, edible stalks. Thrives in cool, sunny spots.
Complete Plant Information
Overview
Rheum × hybridum, widely known as Rhubarb, is a distinctive, clump-forming herbaceous perennial valued by gardeners primarily for its vibrant, tart, edible leaf stalks used extensively in baking and preserves. While ornamental, this plant demands attention to safety, as the large, heart-shaped green leaves contain high levels of oxalic acid and must never be consumed. Successful cultivation of Rhubarb focuses on providing the stable, cool conditions required for the production of these desirable petioles.
This structure emerges annually from thick rhizomes, offering substantial foliage that provides texture contrast in the landscape before mid-summer heat slows production. Choosing the right location is crucial for cultivating a long-lasting stand of this popular garden vegetable. Gardeners planting Rheum × hybridum should remember that while the plant is vigorous, it requires consistent moisture and deep, fertile soil to perform optimally year after year.
Properly managed, the hybrid rhubarb provides reliable harvests over many seasons, becoming a dependable feature in the vegetable patch or perimeter border. Understanding its specific cultural needs, especially concerning temperature stress and soil drainage, ensures that your Rheum × hybridum yields abundant, high-quality stalks ready for pie season.
Fast Facts
- Plant Family: Polygonaceae
- Plant Type: Herbaceous perennial
- Native Range: Cosmopolitan
- Hardiness Zones: USDA Zones 3-8
- Size at Maturity:
- Height: 2-3 ft
- Spread: 3-4 ft
- Bloom Time: May to August
- Bloom Description: White
- Sun Exposure: Full sun to part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
Cultivating healthy Rhubarb requires careful attention to soil structure and planting location right from the start. Best growth occurs in fertile, sandy-humusy, slightly acidic, medium moisture, well-drained soils. Plant sections of root divisions (root sets containing one or more buds) 3 to 4 feet apart in early spring, ensuring the crowns are set just below the soil surface.
Consistent moisture management is paramount; Rhubarb needs regular, evenly supplied water, especially during dry spells, as fluctuating moisture can stress the plant. Although adaptable to part shade, Rhubarb thrives best when receiving full sun, though it struggles in intense summer heat above 75 degrees F, potentially requiring annual treatment in the deep South. Promptly remove all flower stalks as soon as they arise to redirect energy back into stalk production.
Divide the root crowns every three to four years to maintain vigor, as overcrowded roots diminish harvest quality. A critical step for new plantings is patience: do not harvest any stalks until the second year of growth, allowing the root system to become fully established before taking a yield.
Landscape Uses
Although primarily grown as a vegetable, the robust foliage and height of Rheum × hybridum make it an excellent architectural component on the border periphery. Plant Rhubarb where its large, heart-shaped leaves can contrast with finer-textured perennials or where its sheer size can anchor a grouping. If harvesting is not the primary goal, positioning it in a perennial border allows gardeners to enjoy its ornamental value without concern for leaf safety.
For those focused on harvest, dedicate a specific, accessible area of the vegetable garden where the roots can remain undisturbed for many years. By ensuring the soil is well-drained, you set up your Rhubarb for long-term success. The stalks offer colors ranging from deep red to pink to green, providing an attractive visual element even before they are prepared for sauces, jams, or pies.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Rheum × hybridum, commonly called rhubarb, is a clump-forming perennial vegetable grown primarily for its edible leaf stalks which are used most often in sauces, jams or pies. Varieties cultivated primarily for cooking fall into the hybrid designation of Rheum x hybridum. This interesting plant typically grows to 3’ tall and to 4’ wide, and features short, thick rhizomes, highly toxic but ornamentally attractive large, heart-shaped, dark green leaves, and edible leaf stalks (long fleshy petioles).
Tolerances
- Rabbit
Potential Problems
Crown rot is a significant threat to Rhubarb, usually occurring when soils are poorly drained or overly wet, leading to decline. For gardeners battling heavy clay soils, using raised beds is highly recommended to ensure adequate drainage around the root zone. Rhubarb is also susceptible to various pests, including stalk borers, beetles, and the rhubarb curculio.
Furthermore, foliage may occasionally develop leaf spots; however, these superficial blemishes typically do not compromise the quality or suitability of the edible crop stalks. Vigilant monitoring and good cultural practices focused on drainage mitigation are the best defense against common Rhubarb ailments.
Frequently Asked Questions
What hardiness zones is Rhubarb suitable for?
Rhubarb (Rheum × hybridum) is hardy and suitable for USDA Zones 3 through 8, requiring protection or annual replacement in hotter regions.
How large does Rhubarb grow?
This perennial vegetable typically reaches a mature height between 2 and 3 feet tall and spreads outward 3 to 4 feet wide.
What sun exposure does Rhubarb need?
Rheum × hybridum performs best when situated in full sun, although it can tolerate partial shade, which might result in slightly reduced vigor.
When does Rhubarb bloom?
Rhubarb produces small, whitish flowers usually forming terminal panicles anytime between May and late August, depending on seasonal conditions.
Conclusion
Rheum × hybridum offers gardeners a rewarding combination of ornamental presence and highly useful culinary material, making it an essential addition to many yards. Providing fertile, well-drained sites and managing moisture levels are key to harvesting the tart stalks of this perennial Rhubarb. Before planting, always confirm your local climate falls within USDA Zones 3 through 8 for the best long-term success.
Companion Planting
Rhizomatous plants like Rhubarb, which require consistent moisture and significant root space, benefit from companions that do not aggressively compete for nutrients across the topsoil horizon. Consider planting shallow-rooted herbs such as chives or parsley around the periphery of the Rhubarb patch; these often enjoy similar feeding requirements without significantly impinging on the large root mass of the Rheum × hybridum.
Another successful pairing involves cool-season leafy crops that appreciate a little afternoon shade cast by the tall foliage come mid-summer, such as spinach or lettuce. By planting these shade-tolerant crops near the rhubarb, you maximize the productivity of that corner of the garden during the hottest part of the year.
Propagation Tips
The most reliable method for propagating Rhubarb is through root division, a task best saved for early spring or early fall when the plant is actively growing but not actively setting seed. To divide, carefully lift the entire clump using a sharp spade, ensuring you do not damage the central crown excessively.
Once excavated, use a sharp, clean knife to cut the crown into sections, making certain that each division retains at least one healthy bud or “eye” along with a substantial amount of root material. Replant these divided sets immediately at the recommended spacing, remembering the crucial rule: do not harvest stalks from divisions until the following growing season.
