Rhubarb (Rheum rhaponticum) originates from China and is a member of the Polygonaceae or dock family. The main part of the plant is the crown which is semi-woody and perennial. It is valued for its long, thickened, red stalks — up to 75cm long — which arise from the crown and carry the large leaves. The stalks are used as a dessert — mostly in pies — and have an acidic taste. They contain useful levels of acids (pH 3.0–3.6), sugars, fibre, protein, potassium, calcium, magnesium and vitamin C. The leaves are poisonous and may contain high levels of oxalic acid.
In Western Australia, a small amount is grown commercially throughout the year for the domestic market, mainly in the Wanneroo area. Local production is lower in the cooler months but imports from Queensland supply the market from April to October.
Climate and soils
Rhubarb grows best in cool to warm conditions and yields and quality decrease as the temperature rises above 27°C. The stalks colour best in cool temperatures. It will withstand slight frosts. Heavy frosts may cause dieback but the plants will resume growth with the onset of favourable conditions.
Rhubarb is a deciduous plant in Europe. In Western Australia it retains its leaves throughout the year but is less vigorous in winter.
Rhubarb is adapted to a wide range of soils in the pH range of 5.5 to 6.5 as long as they are well drained and prepared with large amounts of added organic matter such as conditioned poultry manure or compost.