Rhubarb

Growing Conditions

Growing Zones

Thrives in USDA Zones 3 - 8

Companion Planting

When to Plant

• Transplant

  Plant dormant crowns in early spring as soon as soil can be worked, or in autumn 6 weeks before hard frost

• Harvest

  Beginning in year 3, harvest stalks from mid-spring through early summer when they reach 10–15 inches; pull and twist stalks at the base rather than cutting; stop harvesting when stalks thin noticeably to allow crown recovery

Organic Growing Tips

• Top-dress crowns each spring with 2–3 inches of finished compost or aged manure to feed the deep root system and maintain soil structure

• Apply worm castings around the crown perimeter when stalks begin to emerge to give a gentle nitrogen boost without burning

• Mulch with straw or wood chips after the ground warms slightly to retain moisture, suppress weeds, and keep roots cool during summer

• Brew compost tea from well-finished compost and apply as a soil drench in early spring and again after the harvest season to replenish microbial activity

• Remove flower stalks as soon as they appear to redirect the plant's energy back into stalk production and crown building

• Avoid planting rhubarb where water pools after rain; raised beds or gently mounded planting sites prevent crown rot, the most common organic-garden failure

Common Pests

• rhubarb curculio
• aphids
• slugs
• crown rot (Phytophthora)

Taxonomy

Kingdom

Plantae

Family

Buckwheat family (Polygonaceae)

Genus

Rheum

Species

Rheum rhabarbarum

Natural History

Rhubarb's cultivated ancestry traces to western China and the adjacent regions of Siberia and Mongolia, where related Rheum species were gathered for their dried roots and traded westward along early caravan routes. The genus name derives from the Latin rhabarbarum, meaning roughly "barbarian root from the Rha River" (the Volga), reflecting the plant's exotic origins to medieval Europeans who knew it mainly as an imported medicine. Garden cultivation of the leafstalk as a food plant developed primarily in Britain during the late 18th century, accelerating when sugar became affordable. Rhubarb's deep, fleshy crown and requirement for cold winter dormancy make it uniquely suited to northern climates where few perennial vegetables thrive.

Traditional Use

Dried rhubarb root has one of the longest recorded medicinal histories of any plant in the Old World, appearing in Chinese pharmacopoeia texts dating to at least the first century CE and traded to Europe as a costly drug for more than a thousand years. European physicians from the medieval period through the 18th century prized imported Chinese rhubarb root far above the plant's culinary stalks, considering it among the most valuable trade commodities of the apothecary. The edible stalks were a later European culinary development that became widespread only after the plant's medicinal root trade had already established its cultural presence.

• Traditional Chinese Medicine, Shennong Bencao Jing and later pharmacopoeia texts, from at least the 1st century CE onward - dried root and rhizome

  Dried Rheum root (da huang) was documented as one of the classical purgative drugs in foundational Chinese materia medica texts, prescribed by physicians for constipation, fevers, and abdominal conditions; it remained a core pharmacopoeia entry through the Qing dynasty

• European apothecary trade, 13th–18th century - dried root

  Imported Chinese rhubarb root was among the most expensive drugs sold in European apothecary shops; physicians including those trained in Galenic traditions documented its purgative properties, and the root was sometimes weighed against gold in trade records

Rhubarb leaves contain high concentrations of oxalic acid and are toxic if eaten in quantity; only the stalks are safe to eat. The roots contain anthraquinone glycosides and were used historically only in dried, prepared medicinal contexts by trained practitioners.

This information is provided for historical and educational purposes only and is not medical advice. Always consult a qualified healthcare professional before making decisions related to your health.

Morphology (Plant Structure & Identification)

• Root System

  Rhubarb develops a large, fleshy crown with thick rhizomes and deep, branching roots that store the energy needed to push up stalks each spring; the crown expands outward over years and should be divided when it becomes congested to maintain vigor.

• Stem

  The edible stalks are thick, succulent petioles - t true stems - nging from pale green to deep crimson depending on cultivar; stalks that become thin and wiry signal that the crown is stressed, overcrowded, or exhausted from over-harvesting.

• Leaves

  Leaves are enormous, broadly heart-shaped, and deeply veined, sometimes exceeding two feet across; they are toxic and should be composted or discarded rather than eaten, though they make an effective mulch smothering ground-level weeds when laid around the plant.

• Flowers

  Rhubarb produces tall, branching flower spikes in late spring or early summer that should be cut out at the base as soon as they appear, since flowering diverts energy from crown and stalk development and significantly reduces harvest yield.

• Fruit

  After flowering, rhubarb sets small winged seeds on the dried stalk; seed-grown plants are variable in stalk color and vigor compared to crown-divided plants, making seed propagation less useful for home growers seeking consistent quality.

Known Varieties

Common cultivars worth knowing

• Victoria

  An heirloom variety dating to the 1837 London Horticultural Society exhibitions, producing large, predominantly green stalks with red speckles and excellent tart flavor; reliably productive and widely adapted.

  Best for: Cooking, pies, and jam; the most commonly available heirloom crown

• Crimson Red

  A deeply pigmented cultivar with uniformly red stalks from base to tip, retaining color after cooking; slightly sweeter than green types and very ornamental in the garden.

  Best for: Pies, preserves, and fresh use where red color in the finished dish matters

• Canada Red

  A cold-hardy selection bred for performance in zones 3–4, with sweet, tender red stalks and strong crown vigor after harsh winters.

  Best for: Cold-climate gardens in the northern US and Canada

• Glaskins Perpetual

  A faster-maturing variety that tolerates light harvest in its first year and produces stalks over a longer season than most; less cold-dormancy dependent, making it marginally better for mild-winter regions.

  Best for: Growers in zones 7–8 or those wanting an early productive crown