Rhubarb is not fussy as to soil but should be planted in slightly raised beds if the soil is very heavy. It does, however, need an open site as it will not tolerate shade. Prepare the soil carefully by digging to two spits (spade depths), the roots go deep, and work in plenty of farmyard manure or compost as you go. In choosing a site remember that the leaves are heavy and reach at least 2 feet (60 cm) all round the crown. All varieties of rhubarb develop a deep root system and grow best in a fertile, partially shaded, free-draining soil. Start digging over your soil four weeks before planting, removing any stones you find and adding as much organic matter as possible. Plant in sun or partial shade, on moist but well-drained, humus-rich soils.
Keep in mind that many varieties grow to be very large plants, and require a lot of space. Before planting, dig a hole with a trowel a little bit wider than the crown/plant. The depth should be such that the top of the plant is at, or just below the soil surface. Gently firm the surrounding soil and water well. Spacing between plants should be about 75cm (30in) for smaller varieties, and up to 120cm (48in) for larger varieties.
After the leaves have died down, spread a new layer of compost around the plant to conserve water and suppress weeds. Dead-head flowers immediately after they appear in the early spring, as allowing flowers to set seed will weaken the plant. In order to keep the plants healthy, rhubarb should be divided every five or six years during
winter, when dormant. Each plant can be split into three or four separate crowns with a spade. Make sure each crown has an ‘eye’, or a large bud that will provide next year’s shoots. Dig out a hole slightly larger than the divided plants and place the crown in the hole with its roots facing downwards. The top of the crown should be 2.5cm (1in) below the soil surface. Mark where the crown has been planted with a cane or stones until new shoots appear above
the soil surface in late February or March. Rhubarb suffers from few diseases. Crown rot is the main threat, particularly if soil conditions are wet. The fungal infection occurs at the base of the stalks where crowns turn brown and soften. Plants suffering from rot should be dug up and destroyed immediately. To avoid crown rot,
make sure rhubarb is planted in fertile, well-drained, weed-free soil.
This simple process provides an earlier harvest of sweeter stems that don’t need peeling. For forcing outdoors, cover plants with a container or large pot to exclude the light. Place the cover over the rhubarb as soon as it begins to show signs of growth. For forcing indoors, lift whole crowns in November and place them on the soil surface to be chilled for two weeks in order to break their period of dormancy. Pot each crown up with compost and bring into a cool greenhouse. It’s important to completely exclude any light by placing forcing pots or black polythene over crowns. The lack of light and the heating effect of the cover will quickly cause the rhubarb to ripen and it will be ready to eat within four weeks.
Allow rhubarb to establish for one year before taking your first harvest. Select three of the largest stalks, waiting for the leaves to fully open before pulling from May to August. Stalks are harvested by gently twisting the stems and pulling from the base of the plant. Leaves shouldn’t be eaten as they contain oxalic acid and are poisonous.