Helen Simpson, from the Mushroom Shed, tells you all you need to know about growing rhubarb. She has also written articles about growing basil, brassicas, chilli, coriander, cucurbits, garlic, ginger & turmeric, mint, raspberries, strawberries, tomatoes and lesser known herbs.
I often hear stories about a rhubarb plant still vigorously producing, even if planted many years ago. Often the ‘crowns’ are taken to a new home when a house is sold, or handed down through family generations. Rhubarb is becoming popular to grow again – so how is it done?
Crowns or seed
Most people grow their rhubarb plant from a ‘crown’, which is the part of the plant under the ground and consists of a rhizome and a bud. However, rhubarb can also be grown from seed. Rhubarb grown from seed will take longer. Growing from a crown gives you a good head start.
Crowns can be divided from the main rhubarb plant every five or so years – a plant that has several good sized, distinct growing points indicates divisions may work and they can usually be divided into about three parts. When digging up the crown(s), the crowns may fall apart from each other easily, but generally I’ve had to wrestle with them and split with a spade. The more care taken the better, as damaged crowns can take a while to recover.
Crowns are normally divided when the plant is dormant or growing slowly, e.g. late winter. Once separated, crowns can be re-planted about 90cm apart. Plant the crowns with roots downwards – each crown should have one or more white/pink ‘buds’ or growing points. The recommended depth is to have the top of the crown 3cm under the soil. However I’ve found to reduce the chance of rotting, planting the top of the crown slightly above the soil works best.
Soil and watering
Rhubarb is a perennial and normally stays in position for years. So it is worth making the effort to plant in a good, rich, well-drained soil. Too soggy and your crown may rot. Too few nutrients and you will get thin stalks and a small plant.
With generous nutrients and sufficient water, your rhubarb plant should reward you with an abundance of thick, long, juicy stalks. If this is not the case, try feeding with a liquid fertiliser or sprinkle fertiliser near the base of the plant and water well.
Note, however, that your rhubarb will go through a winter dormant period where, depending on the variety, it will produce fewer or no stalks.
A sunny position is best, however steer away from the hot afternoon sun in summer. Rhubarb will grow in some shade, but will be smaller and thinner.
Rhubarb is best planted in the garden where it can spread out. I have seen old crowns as big as basket balls. It can be grown in a pot but make sure it is a very large one.
Someone told me to only harvest rhubarb in months containing the letter ‘r’, eg: October, November, February etc. There seems to be some truth in this, as no winter months contain the letter ‘r’ and this is when rhubarb is the most dormant. Generally, however, if your rhubarb is producing well, go ahead and harvest it. Giving the stalks a brisk pull downwards and sideways from the main plant will separate them without damage. Leave at least four stalks in the centre of the plant to keep it viable.
Discard the leaves, which are poisonous due to oxalic acid content, as are the roots. During the food shortages of World War 1, rhubarb leaves were promoted as a food source in the UK, leading to the discovery of their poisonous nature.
Rhubarb keeps well in the fridge, however if you forget about it, look out, as you can be left with a soggy mess. It can also be cooked down and frozen. Rhubarb must be cooked, and combines well with apple, cinnamon, orange, berries and pears.
‘Going to seed’
Sometimes your rhubarb plant may produce a seed head. Unless you want seed, I recommend cutting it off as, otherwise, production of the plant will stop for a while.
No, it is not unripe. There are varieties of rhubarb which have mainly green stalks with minimal red colouring – Victoria is probably the greenest. They tend to be extremely productive and still taste good. I mix the vast bulk of the green stalked rhubarb with the lesser bulk of the red varieties, to get both quantity and colour. However, I find the green variety takes longer to cook down.
Finally, red rhubarb stalks can look greener in hot weather and redder in winter.