Grow at Home: adding Rhubarb crowns to your plot•
Posted on 22 February 2021
Rhubarb is a really striking plant to add to your plot. It is a hardy perennial and the stems are most often used as a dessert but are also delicious used in jams and cordials. Weird considering it is technically a vegetable!
It is possible to grow rhubarb from seed, but we have never met anyone who has. If you do want to try and grow your own then, sow it outdoors in Spring. Then as the seedlings appear be very ruthless and thin to 30cm (12") apart choosing only the strongest plants.
Usually gardeners start with Crowns though which are part of the root of an established parent plant. It is much more common to inherit part of a plant from a neighbouring plot holder (they need dividing every so often) or buy a crown from a garden centre.
The crowns go dormant over winter so late Autumn is a good time to plant them - then they can start to grow again in Spring.
Rhubarb can be grown in the ground or in a large container about 50cm (20in) deep and wide. For growing in the ground you will need an open, mainly sunny space with moist, free-draining soil. Bear in mind when choosing your spot that rhubarb can rot if it is allowed to get waterlogged in winter. Also, avoid frost pockets as late frosts can damage the young stems as they emerge.
Once you have chosen your spot, dig in a good amount of well-rotted manure into the soil. Dig your planting hole and position the plant so the tip of the crown is just visible above the soil. They get big so space the plants 75–90cm (30–36in) apart if you are planting more than one.
Keep your crown watered, especially if the weather is dry. It is important to weed regularly and mulch with well-rotted manure or garden compost. This is needed both in the first years to help it establish, and annually in Autumn to keep it growing well. Make sure you don't cover the crown as it may rot if you do.
In early Spring, feed with a general purpose fertiliser according to the pack instructions.
The leaves will die back in Autumn as the crown becomes dormant again. When this happens, remove the dead leaves. This will reduce the likelihood that fungal spores will take hold over winter and will also expose the crown to frost which will help break dormancy and promote a good crop next year. With a little bit of attention, rhubarb plants should last a good 10 years.
This is not something for the first two years but you might want to do this once your plant is fully established. You are tricking the plant and 'forcing' it to provide a crop around 3 to 4 weeks earlier. You may not think this is a timeframe worth the effort, but when you consider there is virtually no other fruit coming out of the garden in March then why not give it a try?
To do this, you need to exclude light from the plant in late winter. There is a specific bit of kits for this known as a forcing jar - traditionally made of terracotta - but you can use a large upturned pot, bucket or bin around 45cm high or taller. Block any holes in your chosen cover to ensure the plant is in complete darkness. Your plant will panic and send pale, tender stems up searching for the light. Check every week and when these reach the top of the cover (about 5 weeks) they will be ready for harvesting.
All this growth takes a lot out of the plant. So, forced rhubarb plants will not usually produce much of a crop later in that season. Therefore you may want to have some plants you force and some you don't.
Splitting, or dividing rhubarb crowns is a good thing for the plant and gives it new life, It is easy to do – dig the existing crown up, then cut it into sections using a spade or garden knife. Try and ensure that each section has 2 or 3 buds and a good number of roots. Chop out any old, woody material from the centre. Replant the new crowns you have created according to the planting instructions for a new crown as outlined above.
As we said above, do not harvest the stems from your plant in the first year. In the second year resist again if you can but if growth appears very vigorous then you could pick just a few stems. In subsequent years you want to be harvesting between a third and half of the leaves to allow the plant to carry on thriving. Reduce your harvesting after June as you could weaken the plant and leave it without enough resources for active growth.
How to harvest - its very tempting to snap stems off but instead, hold the stalk at the base, gently twist and pull upward to ease it out of the ground. Worth noting that only the rhubarb stalks are edible. Never eat rhubarb leaves as these are extremely poisonous – just add those to the compost heap.
Pest & Diseases
Crown rot is caused by fungi or bacteria infecting the crown. When your plant is suffering from this it will look wilted and sickly. If left unchecked crown rot will cause the plant to die. To save the plant, cut back into healthy tissue and remove all affected areas.
Slugs and snails You can find your young stalks nibbled by these. Combat it with a Slug buster beer trap or whatever your preferred method of slug/snail warfare is!
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