Rhubarb
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Overview:
Rhubarb is a vegetable that once it becomes established, will produce a crop with a minimum of aftercare.
It is frost resistant, in fact it requires a period of frost to perform at its best.
It succeeds best in areas where it is subjected to around two months freezing winter weather, followed by a long cool spring.
Another advantage is, it produces its crop at a time when there very little else ready to harvest in the garden.
The tangy tasting green / red stems of this plant can be used stewed and/or as a pie or crumble filling.
It is also used as an ingredient in jam and wine making.
Only the stems should be eaten, the leaves contain oxalic acid and are poisonous.
New Season's Growth
Young leaves forming
Plant Developing
Stems beginning to Ripen
Rhubarb requires fertile well drained ground soil, partial shade and ample growing space.
They have a deep root system, and this should be catered for, when selecting the growing area.
In areas of shallow soil, form a mound of soil or a raised bed and add as much organic matter as possible to it.
Cultivation
Week 9>
Apply a dressing of sulphate of ammonia at 60g (2oz) per sq m to established plants.
Do not over-feed with nitrogen-rich fertiliser as this can encourage flowering.
Week 13:
Plant out new plants 750-900mm (30”-36”) apart in deeply dug, well manured ground.
Crowns of varieties with small buds should be covered with about 25mm (1”) of soil, but large-budded sorts should be set with buds just above soil level.
Newly planted crowns should not be cropped until the second growing season, any flower stems that appear should be cut off, to avoid weakening the young plant.
Apply a generous mulch of organic matter, e.g. garden compost, composted bark or well-rotted farmyard manure to established and new plants.
Spread it around rather than over the crowns.
Week 15:
Sow rhubarb seeds thinly in 25mm (1”) deep drills in the open and thin out in stages until they are 250mm (10") apart.
Rhubarb grown from seed will take at least two seasons to mature enough, to reap a harvest.
Buying one year old crowns is a speedier option.
Week 17:
Check rhubarb in forcing jars or under buckets to see if it is ready for harvesting.
If it is, grab the stalk close to its base and pull it outwards and upwards to remove it cleanly without damaging the central bud.
Carefully replace the forcing jar /bucket back over the clump, checking every few days to see if there's any more rhubarb ready to pull.
After harvesting, remove forcing jars / buckets so that the plants can receive full light, and give the clumps a liquid feed.
Week 24:
Continue picking stems from unforced plants for a few more weeks, then leave plants to replenish their reserves.
Watch out for developing flower stems and cut them away at the base as soon as they are visible.
Once cropping is over and the leaves have died back, remove any plant debris then spread a layer of compost / rotted manure around the plant to conserve water and suppress weeds.
Harvested Stems
Emerging Flowerhead
Flowers fully open
Week 45-10:
Lift four to five year-old crowns when dormant in preparation for division.
Take care when carrying out this task to avoid damaging the thick roots.
Divide the crowns into sections with a sharp spade, each with some healthy roots and at least one strong bud.
Check for signs of hollow crowns (crown rot) disease and discard all infected material.
Replant the divisions with the growing point at, or just below, the soil surface.
Space plants about 750mm(30") apart for small varieties, and up to 1200mm (48") apart for large varieties.
Prior to replanting, cultivate the soil, remove any perennial weeds, and incorporate copious amounts of organic matter.
Week 51:
In preparation for forcing, select a few suitable crowns and leave them sitting on the surface of the soil to allow the frost to get at them.
Forcing is a process that provides an earlier harvest of sweet tender stems.(This can be done either indoors or outdoors)
Indoors;
Lift whole crowns and place them on the soil surface to be chilled for two weeks in order to break their period of dormancy.
Pot up each crown in compost and place the pot/s into a cool greenhouse, shed or garage.
Exclude any light by placing forcing pots or black polythene over potted crowns.
The lack of light and relative heating will quickly cause the rhubarb stems to develop.
Regularly check under the covers to see progress, harvest stems when they have grown in excess of 300mm (12") in length.
Forced crowns* should be replanted outdoors at an appropriate time.
* Do not expect a crop from these weakened crowns for another couple of seasons, i.e. until such time as they recover from the forcing process.
Outdoors:
Place covers (upturned pots or buckets) or forcing jars over the rhubarb as soon as it begins to show signs of growth.
Regularly check under the covers to see progress, harvest stems when they have grown in excess of 300mm (12") in length.
Harvesting:
Allow rhubarb to establish for one year before taking your first harvest.
If you are tempted to harvest some of the first years crop, keep this to a minimum and certainly do not crop any more than 50% of the crop.
Stalks are harvested by gently twisting the stems and pulling from the base of the plant.
Pests and Disease:
Rhubarb suffers from very few diseases.
Occasionally they can suffer from Crown Rot if the soil conditions become exceptionally wet.
The fungal infection occurs at the base of the stalks and the crowns turn brown and soften.
Affected plants should be dug up and destroyed.
Control:
None! other than making sure the plants are planted in well-drained soil.