Latin Name – Rheum x cultorum
Sowing Instructions –
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.
Hints and Tips –
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
For spring sown seedlings, transplant outside when the plants about 3 to 4in tall.
For autumn sown seedlings, plant them outside in early April, 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.
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.
Seeds – 50