What Soil pH Does Rhubarb Prefer and Can It Be Too Acidic?

Rhubarb is more tolerant of a range of soil conditions than many garden vegetables, but it does have a clear preference for a slightly acidic to neutral soil pH. Understanding the pH range in which rhubarb performs best — and the signs that the soil is outside that range — helps you create conditions for a more productive and long-lived crown.

The ideal pH range for rhubarb

Rhubarb performs best at a soil pH between 6.0 and 6.8. Within this range, nutrients are readily available and the root system functions efficiently. It will tolerate slightly more acidic conditions (down to about pH 5.5) without significant problems, and will grow in mildly alkaline soil (up to about pH 7.5) though with some reduction in performance. Below pH 5.5 or above pH 7.5, nutrient availability becomes significantly impaired.

Signs of too-acidic soil

Rhubarb in soil below pH 5.5 may show poor overall vigour, pale or yellowish colouring, and stunted growth. Very acidic conditions also increase the solubility of aluminium and manganese to potentially toxic levels. If you are in doubt about pH, a simple soil test (available from any garden centre) takes the guesswork away. Applying garden lime or ground limestone in autumn at the recommended rate raises pH gradually — do not overlime.

Signs of too-alkaline soil

In chalky or recently-limed soils above pH 7.5, iron and manganese become unavailable and interveinal chlorosis (yellow leaves with green veins) is common. Improving with acidifying materials — sulphur chips, ericaceous compost, pine bark mulch — and avoiding any further liming corrects this over time.