Growing Rhubarb - the essential guide on how to grow Rhubarb
Growing Rhubarb is relatively simple in cool climates and unlke most vegetables rhubarb is a perennial and so can be left in the ground and will return a crop for many years (around 10 to 15 years). Rhubarb is quite a hardy crop and is able to withstand lack of water. Apart from applying fertiliser rhubarb will survive and produce good yields with little other tending.
Used in combination with sugar - in crumbles, yoghurts, pies, trifles, fool or just with custard, Rhubarb is a very popular home grown vegetable.
Do not eat the rhubarb leaves or roots as they contain oxalic acid which is poisonous.
It is advisable and worth the effort to prepare the soil adequately before planting as the rhubarb will rely on the soil for a number of years to come, not just this year. Dig the soil to a good depth and introduce a high level of well rotted organic matter such as manure or compost into the soil to provide nutrients and a good soil structure. Do this about a month before planting to allow time for the soil to consolidate.
Make sure to remove as many weeds as possible as rhubarb doesn't like to be disturbed once established and so avoiding heavy weeding at a later stage is prefereable.
Rhubarb is best grown from rhubarb crowns rather than growing from seed. Rhubarb should be planted in early spring and requires low temperatures (around 40 deg F) for it to break its winter dormancy and renew growth.
Crowns should be planted about 10cm below the soil surface with the crown bud about 2 inches below the soil surface. Any young shoots that exist should just break the soil surface.
Spacing of the crowns will depend on variety but around 60-80cm is right for many varieties such as the popular Victoria.
Rhubarb will grow well in part shaded areas. Rhubarb does not grow well in high temperatures. Avoid positioning in frost pockets.
A severe frost will have a damaging effect on rhubarb and may cause the oxalic acid from the leaves to enter the stalks. For this reason you should remove any stalks that have been effected by a hard frost and place them on the compost heap. The oxalic acid will be broken down successfully by decomposition on your compost heap.
Rhubarb can be grown in acidic soils down to about pH 5.0 but grows best in slightly acidic soil - pH 6.0-6.8.
Rhubarb likes a well drained, fertile soil that contains a good amount of organic matter such as well rotted manure or compost.
If the soil is not well drained then waterlogging can result in the crowns rotting.
Rhubarb requires little tending but with just a little effort you will achieve a much better quantiy and quality of crop.
The growing season of Rhubarb can be brought forward by covering the crowns with a cloche (a cut clear plastic bottle will do) in early spring.
If flowering seed stalks develop then cut them as soon as possible. The seed and flower production will reduce the leaf stalk yield as the plant diverts energy into flower and seed production.
Make sure to weed around your rhubarb plants regularly as weeds can have a damaging effect on plant growth. Do not hoe to deeply and disturb the roots. Remove any leaves that are yellowed or have fallen to the floor level (such as in the picture below).
Adding fertilizer such as well rotted manure each year will increase your rhubarb yield significantly. Fertilise in early spring before plant growth and also before the end of autumn. As well as increasing available nutrients the fertiliser will act like a mulch and improve the water retention properties of the soil and also reduce weed growth.
If adding manure/compost be sure not to cover the rhubarb crowns as this can lead to them rotting.
Do not use fresh manure as this can burn the crop.
After the first hard frost of winter you should remove any remaining stalks and add them to your compost heap.
You may want to thin your crowns every 4-5 years if they are getting overcrowded or you wish to use part of the crown to start another plant. When the stems of the plant begin to become thinner and they are visibly crowded it is a sign that the plant is ready for dividing.
To do this carefully dig up the crown and then divide the crown into sections ensuring that you have at least one bud and two inches of root on each section. You can normally obtain about 4 to 8 new root sections from a crown. Rhubarb crowns should be split in early spring when new growth is just visible.
Harvest rhubarb either by cutting the stems at soil level or by pulling up the stems. You can harvest about 3 or 4 stems at a time per plant whilst leaving some stems remaining to generate the plants energy and growth reserves.
Do not harvest the plant in the first year as the nutrients produced by the leaves should be channeled back into the roots to ensure a strong root system for stem production in the following years growth. In the second year harvest a couple of stalks per plant and after that you can harvest as normal.
DO NOT eat the rhubarb leaves as they contain high levels of oxalic acid which is toxic.
To promote more vigorous growth the next growing season do not harvest all the leaf stalks.
The harvesting season can be extended by 'forcing' the rhubarb. Rhubarb can be forced in winter by covering the crowns with large pots which prevent light reaching the crowns. Forcing can be helped by adding straw or heat producing fresh horse manure inside the pot (but not directly on the crown). The pots pictured below are very attractive terracotta forcing pots but you can use any container that will prevent light reaching the Rhubarb such as an old bucket, box, trug etc.
Many people sing the praises of forced Rhubarb due to the fact that it tends to produce very sweet and tender stems as well as giving a crop many weeks ahead of unforced Rhubarb. When you have picked the tender stems take the container away and let the plant grow as normal to help it to replenish its energies. The next year, choose different crowns for forcing. This rotation of the forcing duties ensures that each plant has time to recover from the extra strain put on it from forcing.
Rhubarb is available in both red leaf stalk and green leaf stalk varieties. Common varieties include
- Victoria - produces Green stems and is fairly easy to grow
- Champagne - considered one of the best varieties for forcing - pale pink stems
- Goliath - thick stalked, high yield crop that is great for forcing.