Sowing: Sow in late winter to spring or late summer to autumn. The seeds are encased in a rather large paper-like shell. Soak the seeds in water for a few hours before planting. Plant the seeds in a peaty mixture or into peat pots to making transplanting them easier and then put them in a sunny window. Rhubarb seeds germinate quickly.
Position: Good garden drainage is essential in growing rhubarb, planting in raised beds helps ensure against rotting of the crowns. Crowns will have longevity of many years, but because of diseases and insects, it is normal to reset a bed after four to five years.
Planting out: For spring sown seedlings, transplant outside when the plants about 3 to 4in tall. For autumn sown seedlings, plant them outside in early October, as the weather turns warmer. Use a mixture of 50% compost and 50% garden soil. Protect the seedlings from the bright sun. Be careful to not over water it as rhubarb can get root rot if the ground is too wet.
Space 1 metre (36in) apart. Much smaller will seriously crowd the plants, result in a diminished crop and increase the likelihood of spreading disease. A two to three year old plant can easily grow to 1.25m (48in) in diameter and 1m (36in) tall. Plant the roots with the crown bud 5cm (2in) below the surface of the soil. Dig the hole for the crown extra large and mix composted manure or peat moss with the soil to be placed around the roots. Firm the soil around the roots but keep it loose over the buds. Water and fertilise the crowns after planting.
Harvesting: Remove the flower stalks as they are seen. During the first year of planting, the stalks should not be picked, since food from the leaves is needed to nourish the roots for the next year's growth. A light picking may be taken during the year following planting, following that: the entire plant may be harvested. When harvesting rhubarb, the first step is to cut the stalks at the soil line or simply pull them out individually. All of the stalks of a plant may be harvested at one time, or pulled out selectively over a 4 to 6 week period. After the stalks are cut, the leaves may be removed.
Preparation for the next year: Rhubarb needs cold to trigger spring growth. Rhubarb tolerates very cold very well, it is hardy to around minus 29°C (-20°F). You don't need to do much, just collect the last few stalks after the first hard frost and throw them on the compost pile and spread a 5cm layer (2in) of compost (or leaves or hay) to prevent winter winds from drying out your roots.
Flowering will reduce the vigour of the plant. The flower and seed stalks should be cut out as soon as they start forming. The plant may still continue to produce the flower stalks so keep cutting. The plants do not become poisonous after flowering starts. The leaves themselves are always poisonous; the leaf stalks can still be cut and used.
Established clumps will have to be trimmed every 4 to 5 years or when the stalks get small and spindly or when the crown is visibly crowded. This will help the plant to keep growing nice thick stems. This is done by digging around and trimming the crown down to 4 or 5 buds. You can also use this opportunity to divide your plant into more plants.
If you haven’t yet tried forced rhubarb, then make it a priority for the forthcoming winter - they're entirely different products. It really is a “gourmet crop” a lot sweeter and more luxurious. The practice of 'forcing' rhubarb, or growing it in dark conditions, didn't start until the early 19th century when a Chelsea gardener made a chance discovery by leaving a chimney pot over one of his plants. He found that depriving rhubarb of light made the stems shoot upwards, searching for light, which made for a more succulent-tasting product. This forced rhubarb is infinitely more delicate than the outdoor garden variety.
The roots, or crowns, of outdoor rhubarb are left in the fields for two to three years and are then lifted, by hand, from November through to Christmas and replanted into low, dark forcing sheds where they are kept warm and moist as the shoots form. The forcefulness of the shoots is such that you can hear the buds bursting, practically crying out as they strain upwards. In a matter of a few weeks the rhubarb stalks are ready to be harvested. As with every other stage of this weird and wonderful plant, nothing is, or can be, mechanised. Nimble fingers pick the luscious pink stalks in true Victorian fashion - by candlelight - to protect the younger stems that are still growing. The telltale sign of forced rhubarb is its incredible colour: a particularly eye-pleasing vibrant pink with curled mustard-yellow leaves. The plants grow in the sheds right up to the end of September, when the outdoor variety becomes available.
The 'Wakefield Triangle'
The right kind of soil, readily available coal from local pits needed to heat the forcing sheds, and good transport links all played a part in concentrating the forced rhubarb industry into a small area of West Yorkshire known as the 'Wakefield Triangle' (with Leeds and Bradford forming the other two 'corners'). In their heyday, the West Riding growers, of whom there were nearly 200, would take tons of rhubarb to be carried on the 'rhubarb express' train to cities in the south. Today there are barely 12 growers left. The industry was dealt a severe blow by imported exotic fruit and rhubarb has become too expensive for many to grow.
How to force rhubarb
1. Start with a small rhubarb rhizome.
2. Put the rhizome in a large pot and cover with soil leaving just the growing bud exposed. Leave this outside in the cold for 3 to 4 weeks. Rhubarb needs to be exposed to several days at freezing temperatures (0°C / 39°F).
3. Bring the pot indoors to a dark and cool (10°C / 50°F) place like a basement or a garage. The rhubarb will grow rather slowly at first while it is growing new roots. After 8 weeks the petiole will be about 20cm (8in) long from the top of the rhizome to the base of the leaf, the rhubarb then starts to pick up speed.
4. Harvest all of the stalks and return the pot to the outdoors for the remainder of the winter. This plant can be re-planted in your garden where it will grow again in the spring.
History: Rhubarb stems did not come into general use as a fruit till about 100 years ago. Joseph Myatt first began market gardening at Mannor Farm, Kent in 1818. He farmed for many years at Deptford and Camberwell, where he achieved great fame as a raiser of strawberry varieties and as the first man to grow rhubarb on a commercial scale. Before this time, rhubarb was mainly an ornamental plant or a food curiosity.