General
Rhubarb is a long-lived, cold-hardy perennial grown for its tart leaf stalks (petioles). Leaves are toxic due to oxalic acid and should never be eaten. Plants form large clumps and can remain productive for 8–15 years if given deep, fertile soil, ample moisture, and regular feeding. Bolting (flowering) is common in heat or stress; remove flower stalks promptly. Best flavor and texture come from spring harvests; refrain from late-season picking so crowns can recharge. Red stalk color depends on variety and light; greenness does not mean poor quality.
Light
Full sun to light partial shade. Best stalk yield in 6–8 hours of sun.
Soil type
Deep, fertile, well-drained loam rich in organic matter. Avoid waterlogged or heavy clay without amendment.
Water requirement
Consistently moist but not soggy. 25–40 mm per week in the growing season, more during hot, dry spells.
Nutrient requirement
High to very high. Heavy feeder of potassium and nitrogen early in spring; prefers generous compost or well-rotted manure.
Precultivation
Seed is slower and more variable than crowns but works well. Soak seed 12–24 h, then sow 1–2 cm deep in modules at 15–20°C. Germination in 10–20 days. Grow on cool and bright to prevent legginess. Harden off well. Crowns (divisions) are the fastest route: plant as soon as the ground is workable in early spring or in early autumn while soil is warm.
Planting
Choose an open, permanent spot with at least 1 m spacing between plants (120–150 cm for large varieties). Dig a deep hole, incorporate 10–15 L of compost and some well-rotted manure. Plant crowns with buds 2–3 cm below the surface; water in thoroughly. For seedlings, set at the same depth as in the pot. Mulch with compost or straw after soil warms. Avoid harvesting in the first year (seed-grown) or first season after division; take only a light picking in year two.
Pruning
Rhubarb is not pruned like shrubs; instead, remove flower stalks as they appear from late spring to mid-summer to focus energy on petioles. Snap or cut spent leaves at the base through summer. In late autumn after frost, clean away dead foliage to reduce disease carryover.
Maintenance
Top-dress in early spring with 3–5 cm compost and a balanced organic fertilizer; repeat a light potassium-rich feed after the main spring harvest. Keep evenly moist with deep, infrequent watering and thick organic mulch (straw/leaves) to conserve moisture and suppress weeds. Divide overcrowded clumps every 5–8 years in early spring or autumn, ensuring each division has 1–3 healthy buds and ample root. Avoid damaging crowns with hoes. Do not allow waterlogging—raise beds if necessary.
Harvest
Harvest when stalks are at least 25–30 cm long and firm, usually late April through June. Grasp a stalk low and pull with a slight twist to detach cleanly, rather than cutting. Never strip a plant bare—leave at least one-third of the stalks to sustain growth. Stop harvesting by early July to let crowns rebuild. Discard leaves safely (not edible). For tender stalks, harvest in the cool morning and refrigerate unwashed for up to a week.
Common issues
• Crown/root rot (waterlogging, Phytophthora): Improve drainage, avoid overwatering, do not bury crowns too deep. Use raised beds on heavy soils. • Leaf spot (Ramularia): Improve air flow, remove infected leaves, avoid overhead watering. • Slugs/snails on emerging shoots: Hand-pick, use barriers, encourage predators; avoid mulches that harbor slugs until plants are established. • Bolting: Remove flower stalks; reduce stress with consistent moisture and spring feeding. • Frost scorch on young leaves: Usually cosmetic; remove mushy tissue and allow regrowth.
Pollination
Not required for harvest. Flowers are wind/insect-pollinated but usually removed.
Companion plants
Alliums (garlic, chives), calendula, nasturtium, strawberries at the bed edge, comfrey nearby for chop-and-drop mulch.
Incompatible plants
Avoid close competition from shallow-rooted shrubs and trees; do not interplant with deep-rooted, thirsty perennials that shade the crown.
