Greenhouse, Garden & Allotment Blog

Growing Rhubarb in Pots

Posted by Alix Francis on 21st Jan 2019

An attractive hardy perennial that tastes delicious and looks beautiful.

Rhubarb plants are exceptionally easy to grow and if well kept will remain productive for at least 10 years.

Like asparagus, rhubarb needs time to grow, get stronger and establish its roots. It doesn’t need as long as asparagus, rhubarb can be harvested after a year.

What You Need to Get Started

  • Rhubarb Crowns
  • A Fork
  • Compost or Well-Rotted Manure
  • Large Pot or Container

Soil Preparation

Dig over your soil a few weeks before planting your rhubarb, removing any stones and adding as much organic matter as you possibly can.

Note that all varieties of rhubarb develop a deep root system and grow best in a fertile, partially shaded, free-draining soil.

How to Grow Rhubarb

Rhubarb thrives in open sunny sites with moisture retaining soil.

You can grow rhubarb from seed or plants (crowns).

Rhubarb grown from seed will take longer to grow and not always guaranteed results, however, it’s not impossible to grow from seed as long as you look after your rhubarb and know what you’re doing.

Buying one-year old plants that have been divided from disease-free plants is highly recommended, it’s easier and will produce you great rhubarb.

Keep rhubarb free from weeds by adding compost or mulch to cover the ground. Avoid burying the crowns as they will rot.

Pot-grown rhubarb can be planted at any time (If you’re not growing in a pot or container, plant dormant crowns between Autumn & Spring)

If growing in pots, make sure they are at least 50cm wide and deep.

Spread out the roots and plant the rhubarb so that the tip of the crown is just visible above the soil.

Space out the rhubarb 75-90cm apart with 30cm between rows.

Cover the area above the roots with general purpose fertiliser in March and be sure to water regularly in dry spells to retain moisture and encourage growing activity.

Remove dead leaves to expose your crowns to the frost, this will break dormancy and ensure a good crop next year.

Once you’ve removed the leaves, spread another layer of compost around the plant to conserve it’s water and suppress any weeds.

If your rhubarb plants starts to flower, remove the flower heads immediately, keeping the flowers on the rhubarb will weaken the plant.

Many rhubarb varieties grow to be very large plants and need a lot of space to grow properly, it’s worth keeping that in mind when planting your rhubarb.

Forcing Rhubarb

You can force rhubarb to produce an earlier harvest.

To do this outdoors you will need to cover the plants with a container or large pot to stop light reaching the plant. Many gardeners use Forcing Pots which are large terracotta pots that cover the plant.

Add the cover over the rhubarb at the first signs of the plant showing growth.

If you’re forcing the plant indoors, lift the crowns in November and place them on the soil surface outdoors to chill for two weeks. This is to break dormancy.

Put up each crown with compost and bring into a cool greenhouse. Be sure to all light is completely excluded.

Lack of light and the heating provided from the cover will quickly cause your rhubarb to ripen and be ready to eat within 3-4 weeks.

You will know that the rhubarb is ready when the stems reach the top of your container.

Common Problems

Crown Rot: Common problem which is caused by various soil or water borne bacteria and fungi. You will notice plants looking sickly and failing to grow with signs of rot at the crown. If ignored crown rot will spread to the stems and foliage will eventually cause your plant to die.

Remedy: Remove affected areas by cutting back into the healthy tissue.

You’ll need to take prompt action to try and save the plant.

Snails & Slugs: These pests love young seedlings, you’ll know when they have been around too as you will see their slime trail on the soil and around your crops.

Remedy: There are many ways you can control these pests. Beer traps, sawdust, egg shell barriers, copper tape and biocontrols are a few methods used to help keep them away from your crops.

Diving Your Rhubarb

Keep your rhubarb plants healthy by dividing them every five or six years during winter when they are dormant.

Each plant should be split into 3-4 crowns and planting separately. Make sure your crown has a large bud which can produce shoots next year.

Harvesting Rhubarb

Do not harvest your rhubarb during it’s first year, it reduces growth and the plants strength.

Start by removing a few stems in it’s second year, then increase your harvest as time goes on but leaving some there to keep the plant healthy and active.

To remove, hold the stalk at its base and ease it out of the ground. Try to avoid snapping the stalk off.

Do not eat rhubarb leaves as they are full of oxalic acid and are poisonous.

Seasonal Rhubarb Advice

Although rhubarb is one of the easiest crops to grow, knowing a little more about how to care for them during the different seasons goes a long way and will help you to produce better crops.
  • Spring: Boost your rhubarb with a general fertiliser to encourage growth and remove rhubarb flowers to stop the plant focusing and using its energy on growing the flowers.
  • Summer: Keep your plants watered well during dry spells especially if grown in pots and containers.
  • Autumn: Leaves will die naturally and will need cutting back to leave the bud exposed. Mulch and good quality compost should be applied around the crown of the plant to help keep the moisture in the soil and keep the weeds away. Be sure not to cover the crown as this will cause root rot.
  • Winter: Lift and divide your rhubarb every 5-6 years to ensure plants remain healthy and productive. Use a spade to lift the crown and split the rhubarb into 3-4 pieces, replanting them separately.

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