Top Of The Crops - Beetroot

Originally grown in coastal regions, beetroot is now a reliable favourite in any kitchen garden. Easy to grow (even if you are a beginner) with an excellent yield, beetroot thrives in moist, well-fertilised conditions and doesn’t attract too many pests. It fares best when sown directly into the ground, but you can also grow beetroot in pots, making it the ideal crop for a wide variety of gardeners and gardens across the country. Though the hardiest varieties are simple to grow, this process is even easier in a polytunnel; follow this guide, and you should find yourself producing delicious and plentiful crops in no time.


Not only is beetroot easy to grow and fertile in its yield, but it is also rich in a wide range of nutrients, including iron, vitamins A and C, calcium, folic acid, and antioxidants. Earthy and subtly sweet in flavour, beetroot can be enjoyed raw in salads or juices, cooked into soups, roasted whole, or grated and baked into chocolate cakes and brownies. Beetroot leaves are also delicious – cook them as you would kale or spinach. Luckily, this crop is ideally suited to polytunnel conditions, so you can easily add it to your home-grown vegetable supply for the year.

Using a polytunnel to grow beetroot will benefit your crop in various ways, helping to ward off most pests and extending the sowing and harvesting periods. In unprotected areas, you can sow beetroot from late March until July, but you can extend the growing period dramatically in a polytunnel. With the added cover and protection, you can sow from the beginning of March to the end of August. You can even leave roots to overwinter, providing you with a ready supply of fresh beetroot throughout November, December, and January.

Beetroot tolerates most soil types and conditions. However, if your garden or polytunnel plot is currently empty, it won’t do any harm to tailor the space to your beetroot crop, for which the ideal soil is light-to-medium and either slightly alkaline or neutral, with good drainage.

  • Prepare your ground with organic matter and a general-purpose fertiliser, ensuring that the soil is moist, before sowing.


When sowing beetroot seeds, bear in mind that each seed is a cluster, which can produce up to three or four seedlings. Avoid over-crowding by leaving plenty of space between seeds.

  • You should space your rows 30cm apart, to prevent root-interference. Make your rows by carving furrows (drills) in the earth with the side of a hoe or rake. These should be 2-2.5cm deep.
  • Sow a maximum of one or two seeds per 10cm.
  • Cover the seeds (using your hands or a rake) and water thoroughly. Label each row.
  • If you are sowing in early March, you might want to cover your seeds with a frost-protection fleece, even inside the polytunnel, to reduce any chances of frost-damage whilst the seedlings are in their initial stages.
  • To avoid an excess of beetroot when it comes to harvesting-time, you can stagger this stage, and sow a small batch every fortnight.


The seedling stage is critical for growing healthy beetroot; follow these steps to avoid undernourished crops:

  • When the seedlings are around 2cm tall, remove the weakest of each pair (if you have sown two seeds per 10cm), leaving only one seedling per 10cm. You should use a pair of sharp scissors (or your fingernails) to pinch off the weaker seedlings. Do not pull them out, as this may disturb any tap roots that the beetroot seedlings have already set down.
  • Keep the area around the seedlings clear of weeds and continue to do so as they grow. Use a trowel or hoe, or do so by hand, and avoid chemical weed-killers.
  • Remember to water the plants thoroughly, and make sure the soil does not become dry. In summer, particularly when raising new seedlings in July or August, you might find it useful to install an automatic water system in the polytunnel – especially if you are planning to go on holiday around this time!

Though beetroot is a hardy plant, it can attract some pests and diseases:
Beetroot is particularly prone to bolting (or flowering) when deficient in moisture, nutrients, or space, which can ruin your crop. Avoid this problem by keeping the ground well-watered, laying down plenty of organic matter before sowing, and removing the smaller seedlings if your rows are overcrowded.
Garden birds love beetroot seedlings but planting directly into the ground within your polytunnel should prevent most birds from finding the crop!
Aphids and leaf spot can affect seedlings and young beetroot, too, leading to disfigured crops. Combat aphids by encouraging ladybirds and hoverflies into the polytunnel. A good layer of fertiliser before sowing should be enough to prevent leaf spot.
Leaf miners also feed on young beetroot, producing white tunnels and blisters in the leaves. Look out for evidence of leaf miners in May and remove any affected leaves immediately. Keeping the beetroot under cover in a ventilated polytunnel will offer more protection than in an open garden, however, and should help to prevent most of these issues.


Most beetroot crops are ready when the roots are the same size as a tennis ball or cricket ball. This is typically about three months after sowing but can differ depending on the variety of beetroot you are growing. Do not leave the roots in the ground too long, once they have reached this size, as they may become woody and coarse.

  • To harvest your beetroot, twist and pull firmly on the leaves. If you need to, lever the earth beneath the roots with a fork at the same time. Be careful not to hit or damage the roots during this process.
  • You can also stagger your beetroot supply by pulling up young roots when they are the size of a golf ball.

For beetroot sown in July, August, or early autumn, you can leave the roots in the ground to over-winter and dig up on demand. Make sure to put frost-protection in place, using a frost-protection fleece or polytunnel heater, if your winters are especially cold.

Alternatively, harvest these later crops in September or October, and store them in boxes layered with sand. If storing beetroot in this way, you should first twist off the leaves so that only 0.5cm remains. Do not cut off the leaves, as they will bleed and leach moisture away from the roots. Check that none of the roots are damaged before packing away, as damaged roots can rot and ruin any adjacent roots. Keep these boxes in a cool, dark place.






Harvest First Year

Subsequent Years

Indoors: March to August

October to March

October to March

Outdoors: March to July

May to October

May to October



Plant in March

April and May for young crops, June for mature crops.

April and May for young crops, June for mature crops.


Beetroot will thrive in a polytunnel’s moist, warm conditions, and should manage to avoid most pests too. If you are new to beetroot-growing, try a reliable, bolt-resistant variety such as Boltardy. Cheltenham Green Top, identified by its long roots, is another reliable variety, which is ideal for winter storage. Or, if you’re feeling adventurous, you can experiment with Barbabietola di Chioggia, which will produce a beautiful ‘candy cane’ effect when sliced. Whichever variety you choose, beetroot will soon become a new favourite in your polytunnel beds and in your everyday cooking!

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