watering
Rhubarb will not need watering once it is established – the roots go down deep into the ground to find the available moisture. If the spring is very cold and dry, however, a stressed plant can send up a rather impressive flower spike, showing how it is keen to run to seed and propagate itself. If that happens, remove the flowering spike straight away and water if drought seems to be the problem. If you are growing rhubarb in a pot, you will need to give it a good drink every week whilst it is in leaf.
fertilising
As rhubarb is in for the long haul you need to make sure it is planted in fertile ground. From then on, an autumn mulch should keep it in fine fettle, as long as you do not over crop each plant.
growing in pots
Rhubarb can also be planted in very large pots at least 50cm deep and wide. You will need a fertile loam-based compost (John Innes Number 3), and you will need to water regularly whilst the plant is in active growth. Place your containers in full sun.
harvesting
In the second season (12-14 months after planting), you can start picking when the leaves have fully unfurled and the stems are approximately 30cm long. Never take more than half of the stems at a time – over-cropping will reduce the plants vigour. Stalks are harvested by gently twisting the stems and pulling from the base of the plant. If you grow a good range of early, medium and late varieties you can have a harvest from early spring to late summer.
lifting & dividing
Lift and divide the crowns every 5 or 6 years, between November and March while the plant is dormant. Use a spade to lift each crown, split into 3 or 4 pieces and replant separately. Make sure each piece has a healthy-looking bud, which will become the growth point for next year’s new shoots. Remember the leaves are poisonous to eat but can be safely composted with the rest of your garden waste.
forcing rhubarb
A mature plant can be “forced” to give you a very tender “blanched” crop that will hardly need any sugar. In the old days (and still in the forcing houses of Yorkshire), whole plants were dug up in the autumn and moved indoors to warm dark sheds where they start cropping in the middle of winter. You can try this yourself, especially if dividing an elderly crown anyway, but it does mean sacrificing that section, as they will rarely return from such harsh treatment. However, there is a half-way house, using a fancy terracotta forcing pot, or more prosaically, an upturned bucket.
Early in the new year, select a healthy two- or three-year-old plant and place the forcer over it, surrounding the crown with dry straw or bracken to create some warmth. Replace the lid and watch out over the next seven to eight weeks for the emerging shoots pushing off the lid to show how they are ready to be picked. Pick all the stems off every week until your unforced plants begin to take over in late spring. Remove the forcer and the straw and give the plant a good mulch of well-rotted compost. Do not take any more from this plant for the rest of the year and remember not to force it two years in a row.
