Growing Rhubarb in the UK: A Beginner's Guide

Why is rhubarb such a good crop for beginners?

If you only ever grow one thing in your garden, rhubarb makes a strong case for the job. It is a hardy perennial, which means you plant it once and it comes back year after year on its own. A healthy crown will happily crop for ten, twenty, even thirty years or more, so the small effort of planting pays you back for decades.

It is also one of the very first things ready to harvest in the growing year. While most of the veg patch is still bare soil in early spring, rhubarb is already pushing up fat crimson stalks, ready for the first crumble of the season. That early start is a big part of its charm, and it fits neatly alongside the other slow-and-steady crops in our fruit growing guides.

Best of all, it asks very little of you. Rhubarb is tough, shrugs off cold winters, and is rarely troubled by pests. Give it decent soil, a bit of feeding and the odd bucket of water in a dry spell, and it more or less looks after itself.

Plant a crown once and you can be pulling rhubarb from the same clump long after you have forgotten the day you put it in.

How do you plant a rhubarb crown?

The easiest way to start is with a dormant crown, which is essentially a chunk of established root with a growing bud on top. These are sold bare-root over the colder months and are far quicker to establish than seed. The best planting window runs from autumn through to early spring, roughly November to March, while the plant is asleep. Container-grown plants can go in at almost any time, but bare-root crowns want that dormant season.

Pick your spot with a bit of care, because the plant will be there for years. Rhubarb wants an open, sunny position and rich, fertile soil that holds moisture but never sits waterlogged. It is a hungry plant, so this is the moment to be generous with well-rotted manure or garden compost, dug in before you plant. If you make your own, a barrowload of the good stuff from the heap is ideal, and our guide to making compost at home walks through how to get there.

1. 1

   Prepare the ground

   Clear all weeds and dig in a generous amount of well-rotted manure or compost. Rhubarb is a big, hungry plant that will occupy the spot for years, so it is worth doing this properly.

2. 2

   Dig a wide hole

   Make a planting hole big enough to spread the roots out comfortably, without cramming or bending them.

3. 3

   Set the crown at the right depth

   Position the crown so the growing bud sits just at, or slightly above, the soil surface. On heavy or wet ground, raise it a touch proud of the soil to keep the bud from rotting.

4. 4

   Firm and space

   Backfill, firm the soil gently around the roots, and water in. Allow around 90cm between plants, as a mature crown gets surprisingly large.

5. 5

   Mulch around it

   Spread a layer of compost or manure over the soil around the crown, keeping it clear of the bud itself, to lock in moisture and feed the plant.

The depth point is the one that catches people out. Bury the growing bud too deep and it is liable to rot, especially on our wetter British soils. Keeping that tip at or just above the surface is the single biggest thing you can do to get your crown off to a good start.

Why shouldn't you harvest rhubarb in the first year?

This is the hardest rule to follow and the most important one to get right. In its first year in the ground, a new rhubarb plant is busy building a root system and storing up energy. Every stalk you pull is energy taken away from that job.

So in year one, however tempting those first stems look, leave them all in place. Let the leaves do their work of feeding the crown. In the second year you can take a light first harvest, pulling just a few stalks, and by year three the plant should be fully established and cropping generously. A little patience at the start buys you years of far heavier harvests later.

How do you harvest rhubarb?

Harvesting rhubarb is oddly satisfying. Choose stalks that are a good size, hold each one right at the base, and pull with a gentle twist so it comes cleanly away from the crown. Resist the urge to cut stalks with a knife: a cut leaves a stump behind that can rot and let disease into the plant.

Never strip a plant bare. Take no more than a third to half of the stalks at any one time, and always leave a good number of healthy leaves behind so the crown keeps feeding itself. Pick a few stalks regularly rather than everything at once.

Ease off as summer arrives. The general rule is to stop pulling by around late June or early July. After midsummer the stalks grow tougher and stringier, and the plant needs the rest of the season to recharge for next year. On a well established clump you can sneak the odd stalk later on, but treating midsummer as your cut-off keeps the crown vigorous. All those tart stems are perfect for crumbles, compotes and a proper batch of rhubarb jam, and our guide to making jam covers the setting and potting side.

Are rhubarb leaves poisonous?

Yes, and this is not a point to be casual about.

The good news is that the stalks themselves are completely safe and delicious. The oxalic acid builds up mostly in the leaves, and the amount in the stems is not enough to cause harm. Just keep the two clearly separate in your head: leaves to the compost, stalks to the kitchen.

What is forcing, and how do you do it?

Forcing is the trick behind that gorgeous, pale pink, tender rhubarb you see early in the year. The idea is simple. In mid-winter you cover a crown to block out all light. Cut off from the sun, the plant sends up long, blanched, pink stems that are sweeter and more delicate than normal green-and-red rhubarb.

To do it, cover an established crown in December or January with a traditional tall clay forcing pot, or simply an upturned bucket or bin, packing a little straw around it against the cold if you like. Roughly four to eight weeks later, you will have tender forced stems ready to pull.

Two things to remember. First, only force healthy, well established plants that are three or more years old, because forcing takes a lot out of a crown. Second, give a forced plant a proper rest afterwards: stop harvesting from it once the forced crop is done, let it grow on freely for the rest of the season, and don't force the same crown again for a few years so it can rebuild its reserves. Rotate between two or three plants and you can enjoy forced rhubarb most years without exhausting any of them.

How do you keep a rhubarb plant going for years?

A little upkeep keeps a crown productive for decades. Every autumn or early spring, spread a thick mulch of well-rotted manure or compost over the soil around the plant, keeping it off the crown itself. This feeds the plant, holds moisture and does most of the ongoing work for you. In dry spells during the growing season, give it a deep drink, as thirsty rhubarb sulks.

Over time even the best crown slows down, with thinner stalks and a woody, congested centre. The fix is to divide it every five or six years. In the dormant season, dig the whole crown up and split it into sections with a spade, making sure each piece has at least one healthy growing bud. Replant the strong outer sections in refreshed ground and discard the tired middle. You end up with vigorous plants and, as a bonus, free extras to grow on or pass to a neighbour.

What are the common rhubarb problems?

Rhubarb is remarkably trouble-free, but two issues come up often enough to know about.

Crown rot is the main one. It usually comes from a crown that is sitting too wet or was planted too deep, letting the growing bud soften and rot. Prevention is the cure: plant with the bud at or just above the surface, avoid waterlogged ground, and don't pile mulch over the crown itself.

Flowering, or bolting, is the other. Now and then a plant throws up a tall stem topped with a frothy flower head, often after a hot dry spell or when a crown is getting old and crowded. That flower drains energy away from the stalks you actually want, so cut the whole spike out at the base as soon as you see it. If a plant bolts every year, take it as a nudge that it is time to divide.

Get the basics right and rhubarb rewards you out of all proportion to the effort. One crown, a sunny corner, a barrowload of compost and a bit of patience in that first year, and you are set up for pudding season after pudding season.