Horticulture Magazine

Rhubarb Plant Care & Growing Tips

fresh rhubarb growing in a garden

Rhubarb Overview

Official Plant NameRheum x hybridum
Common Name(s)Rhubarb
Plant TypePerennial Vegetable
Native AreaCultivated
ToxicityToxic Leaves
FoliageDeciduous
When To SowJanuary, February, March, October, November, December
Harvesting MonthsMarch, April, May, June
Sunlight

Preferred
Full Sun

Exposure
Exposed or Sheltered

Size

Height
0.5 – 1M

Spread
0.5 – 1M

Soil

Preferred
Most Soil Types

Moisture
Moist but well drained

pH
Any

Rhubarb is a vegetable that often masquerades as a fruit – but it is far more than just that and can be a very useful addition to your garden.

As a perennial vegetable, rhubarb can be a fantastic addition to a low-maintenance food producing garden. Unlike annual and biennial crops, perennial vegetables like rhubarb will return to provide you with an edible yield year after year.

So, let’s take a closer look at rhubarb. Read on to learn what rhubarb is and why exactly it can be such a good choice. Discover how to choose the right rhubarb for where you live. And how to plant it, care for it, and harvest it from your garden. By the end of this article, you should have a much better idea of whether rhubarb is the right choice for your site, and if it is, how to grow it successfully where you live.

Background & Origins

Commonly cultivated culinary rhubarb plants are classified as Rheum x hybridum. Interestingly, no one knows exactly how these modern culinary garden plants were bred, or their exact origins.

Two different species – Rheum rhabarbarum and R rhaponticum where grown in Europe prior to the 18th Century and were used medicinally. By the early 18th Century, these two species and a hybrid of unknown origin – Rheum x hydridum, were commonly cultivated as vegetable crops in the UK and elsewhere in  northern Europe. The wild plants hybridise easily, and many cultivars have been developed. Culinary rhubarbs share a number of characteristics with their wild cousins, but have botanical distinctions.

shoots of rhubarb growing out of soil
Rhubarb.

People often wonder whether rhubarb is a fruit. Botanically speaking, it is not. It is a vegetable because the part of the plant that we eat is the stalks or stems, not a fruit. However, in culinary settings, rhubarb is often treated like a fruit, since it is used to make sweet dishes in similar ways.

Rhubarb has a strong, tart taste, and while the stems can also be eaten raw, they are usually cooked and mixed with sugar or other sweeteners to make pies, crumbles and other desserts or preserves.

The word rhubarb is believed to have derived from the old French word ‘rubarbe’ in the 14th Century. This, in turn, came from the Latin ‘rheubarbarum’ and the Greek ‘rha barbaron’ which means ‘foreign rhubarb’.

Rhubarb is grown for the fleshy leaf stalks, which are technically called petioles. Their use in a culinary setting is of fairly recent origin – it was recorded in England in the 18th and 19th Century only after sugar became more widely available.

While the petioles are safe to eat in moderation, however, the rest of the plant, including the leaves, is too high in oxalic acid, and contains toxic anthraquinone glycosides. Consumption of other parts of the plant by humans or animals can cause poisoning. So this is something to bear in mind if you plan to grow some in your garden.

Why Grow Rhubarb in Your Garden?

Rhubarb can be a useful way to add to your home grown diet. As mentioned above, as a perennial plant, it requires less work than annual or biennial crops, and will return to provide a yield year after year.

Growing perennial plants in general can be a very good idea. They bring a range of benefits for the garden including:

  • The fact that you will need to do less work in sowing and planting. Perennial plants like rhubarb only need to be planted once and will last a number of years. While annual crops will involve work annually to continue to enjoy them in your garden.
  • And you’ll need to do less ongoing work maintaining soil  too. Growing areas with perennial planting typically require far less care over time.
  • You will also typically spend much less time watering or fertilizing perennial crops than you will maintaining an annual garden over time.

Another thing to consider is that growing perennial plants like rhubarb also benefits the natural world.

  • Perennial vegetables protect the soil, since its ecosystem will not be disturbed by annual cultivation.
  • Perennial vegetables also create a more biodiverse environment – helping to shelter and protect wildlife, and drawing more beneficial life into your garden.
  • What is more, rhubarb and other perennial plants can benefit plants grown around them in a polyculture situation.

As a perennial vegetable, rhubarb can be a great thing to grow for all of the reasons outlined above. But more specifically, it can be a very useful garden plant.

Rhubarb provides a yield during what was historically known as the ‘hungry gap’. This was the time between winter stores running low, and late spring/ early summer harvests. So growing rhubarb means that you will have food from your garden all year – even during times when, historically, there is far less home grown food available. So rhubarb can fill a gap in the home-grown food calender. This is especially true when the rhubarb is forced to bring forward the harvest (more on this below).

Choosing Rhubarb

There are a number of great cultivars for UK gardeners to consider. These include:

  • ‘Early Albert’
  • ‘Giant Grooveless Crimson’
  • ‘Grandad’s Favourite’
  • ‘Hawke’s Champagne’
  • ‘Raspberry Red’
  • ‘Reed’s Early Superb’
  • ‘Stein’s Champagne’
  • ‘Stockbridge’
  • ‘Timperly Early’
  • ‘Victoria’

Planting Rhubarb

Rhubarb will do best in a sunny location, which has fertile and moist yet free-draining type of soil. Make sure you do not place rhubarb in a frost pocket or an area which becomes waterlogged in the winter months.

Young shoots emerging from rhubarb crowns
Young shoots emerging from rhubarb crowns.

Rhubarb is usually grown from crowns. Dormant rhubarb crowns will typically be planted between autumn and early spring.

Position the rhubarb crown so that that the very top of the crown just emerges from the soil surface. Generally speaking, it is best to leave space of around 30-35 inches between the plants. Rhubarb can also be grown in containers, as long as they are a minimum of 50 cm deep and 50 cm wide.

When planting, it is a good idea to add a mulch of homemade compost or well-rotted manure around the plant. This will act as a slow release fertiliser and retain soil moisture. But make sure you do not bury the crown or leave mulch piled closely around it or it can rot.

You can also purchase pot grown rhubarb plants throughout the year. These can be planted out at any time. But to avoid transplantation shock, it is best to avoid planting out these on very hot or dry days in the summer.

Companion Planting With Rhubarb

Rhubarb works very well as one of the plants in a perennial growing area with edible plants. It typically grows well beside other perennial plants – perennial alliums (onions, chives, elephant garlic, for example). Rhubarb also has a scent said to repel whiteflies, and so it can be a useful companion plant for members of the cabbage family. This means it can work well in a perennial bed alongside perennial brassicas such as Daubenton’s kale, tree cabbage, and ewiger kohl, for example.

Place strawberries close to rhubarb, since these will be beneficial as ground cover. They will spread to keep weed growth down and help retain soil moisture. A number of perennial aromatic herbs can also be beneficial as companion plants.

Caring For Rhubarb

Make sure that the rhubarb gets enough water throughout the year, so the plant keeps growing right through to autumn. Make sure that you provide water during any dry spells.

You can also consider optimising yield and vigour by adding a general purpose organic fertilizer in March.

Other than this, however, rhubarb really will require very little care. You have the option of forcing the rhubarb,  but you do not have to do so.

It can also be a good idea to remove the dead leaves when the plant dies back naturally in the autumn. And to clear debris around the crown. This will help make sure it is exposed to frost, which helps break dormancy and ensures a good crop of stalks the following year.

Forcing Rhubarb

a terracotta forcing jar on an allotment
Rhubarb forcing jar.

Forcing rhubarb simply means covering the rhubarb crown to exclude sunlight. This encourages earlier growth (typically around 3 weeks before rhubarb that was not forced), and generates tall pale stems. Forced rhubarb can be harvested when the stems are 20 or 30cm long. And it brings forward to harvest. It is also sometimes argued that forced rhubarb stems taste better than those grown in full sun which arrive later in the season.

It is important to note,  however,that forcing rhubarb robs from future growth – at least to a degree. Only try this trick with  rhubarb plants which are mature and fully established. Young plants may lack the stored energy to generate these early stems. Also, avoid trying this technique with the same rhubarb plant for more than one consecutive year, as this may reduce vigour too excessively.

Late winter is typically the time to force rhubarb, so that you can obtain an early yield in spring. You can start the process as soon as November/ December. But it is usually done in January/February.

In order to force rhubarb, find something to place over your rhubarb. You might use a special rhubarb forcing jar, a plant pot, an old bin, or another random reclaimed container. If using a plant pot, remember to seal up the holes in the base so light does not shine through. Your goal, it should be remembered, is to exclude the sunlight, so avoid using a container which is clear or which allows some light to shine through.

After you have excluded light from the growing stems for 8 weeks, you should be able to remove the cover and harvest.

Harvesting Rhubarb

Rhubarb is usually harvested from March, and then up until June. After this time, the stems will remain edible and taste good throughout the summer. But it is best not to harvest after spring since this can weaken the plant.

When harvesting, hold each stalk at its base and try to ease it out of the ground. Try to avoid cutting or snapping it off.

One important thing to remember, however, is that rhubarb plants should not be harvested at all in their first year after planting. It is best to leave the plants to mature and picking too soon can reduce the vigour of your plants.

You should also be circumspect in the second year, and harvest just a few stems. After that, you can harvest up to a third, or even half of the stems from a mature plant. But you should always be sure to leave some of the plant to continue on in active growth. That way, it will continue to provide you with a bountiful yield for a number of years to come.

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