Why Does My Rhubarb Have Very Small Leaves?

Rhubarb is capable of producing impressively large leaves — 40–60cm across on a well-established, well-fed plant in good conditions. When a plant produces persistently small, underdeveloped leaves year after year, it is operating well below its potential. Small leaves mean reduced photosynthetic capacity, which in turn means less energy stored in the crown, thinner stalks and lower yields. Addressing the underlying cause is what allows the plant to express its full potential.

First year establishment

New crowns and recently divided plants naturally produce smaller leaves in their first growing season. This is normal — the plant is investing in root establishment rather than leaf production. Small leaves in year one are expected; if leaves remain small in year two and three, something else is limiting growth.

Nutrient-depleted soil

Rhubarb is a heavy feeder and benefits from rich, organic soil. In sandy or thin soils, or in sites that have never been improved, the plant may simply lack the nutrition to produce large leaves. An annual surface mulch of well-rotted manure applied around (not on) the crown in late winter makes the most consistent long-term difference to leaf size and overall vigour.

Shade, drought and competition

Shading by surrounding plants or structures reduces photosynthesis and suppresses growth. Rhubarb in shade produces smaller, paler leaves than the same plant in full sun. Competition from tree roots or large shrubs for water and nutrients has a similar effect. Rhubarb performs best with open exposure and no significant root competition within 1–1.5 metres.