Growing Beetroot

Beetroot is closely related to chard, sugar beet and fodder beet, and shares the botanical name Beta vulgaris with them. They all descend from the wild sea beet of the coastlines, but with beetroot the breeding work focused entirely on the root. The Romans brought it to Central Europe, though the deep red colour only appeared through breeding in the 19th century.

It owes that colour to betanin, which is also used industrially as E 162 to colour food. If you only know the classic dark red globe, you are missing a lot: there are yellow, orange and white varieties, red and white ringed ones, and the shapes range from flat-round through globe-shaped to cylindrical and spindle-shaped.

You can eat the leaves too and cook them like spinach, and young leaves are good raw in a salad. Beetroot is grown as an annual, but it is biennial by nature and would flower and set seed in its second year. It is a rewarding crop for anyone starting out in the vegetable garden: tough, rarely troubled and easy to look after.

Sow beetroot directly into the bed from mid-April to mid-July, as soon as the soil reaches 7 to 8 °C. Rush it and you risk bolting, because cold at the seedling stage makes the plant form a flower stem instead of a root. For early sowings, reach for bolt-resistant varieties like 'Boltardy' or 'Rote Kugel'.

Draw the drills 2 to 3 cm deep, with 25 cm between the rows. Sow every 5 to 10 cm in the row and thin to 10 to 15 cm once the seedlings are up. Thinning is nearly always needed, because the seeds come as clusters and one seed produces several seedlings. Varieties like 'Monika' are monogerm and largely save you the job. The thinnings go into the salad bowl as baby leaves.

A few hours soaking in lukewarm water speeds up germination, which runs best at 16 to 22 °C. Raising plants indoors works, but it is unusual because beetroot does not much like being transplanted. If you do, allow around 30 days and harden the plants off beforehand.

For a continuous harvest, sow again every two to three weeks. If you want to store beetroot, plan the last sowing for no earlier than the beginning of June, then the roots are fully mature and ready to store in October and November.

Beetroot wants sun, at least six hours a day. It will still grow in partial shade, but then it stores more nitrate. A spot sheltered from wind is an advantage.

The soil should be deep, loose and rich in humus so the root can swell freely and the taproot beneath it can grow down deep. Beetroot does not tolerate waterlogging, which quickly leads to rot on the roots.

The good pH range lies between 6.5 and 7.5, so neutral to slightly alkaline. Lime soils that are too acidic, and not only for the sake of nutrient availability: beetroot has a high boron requirement and struggles to take up soil boron at a low pH. The result would be heart rot and dry rot, with hollow dark patches in the flesh.

Compost or well-rotted manure before sowing is ideal. Leave out fresh manure, it only pushes the leaves.

'Boltardy' is the obvious choice for early sowings. This British variety from the 1960s is notably bolt-resistant, forms even dark red globes and gives tender, sweet flesh. 'Rote Kugel' is the open-pollinated classic with good keeping quality, and it resists bolting too.

Shapes and colours are where it gets interesting. 'Cylindra' forms long cylindrical roots that cut into even slices with no waste, ideal for pickling. 'Tonda di Chioggia' from northern Italy shows red and white rings when you slice it and tastes mild, the most decorative variety for the salad board. 'Boldor' is yellow-orange and does not bleed when cooked, 'Albina Vereduna' is white and equally mild.

For storage, 'Robuschka' is worth it, a biodynamically bred, open-pollinated variety with smooth skin and a fruity, sweet flavour. 'Ägyptische Plattrunde' is the old flat-round traditional variety and matures early. And if thinning annoys you, take the monogerm 'Monika'.

Water beetroot evenly, above all during germination and in dry spells. Once the roots start to swell you can ease off, because too much water pushes the leaves at the expense of the root. If a long dry spell suddenly turns into heavy watering, the roots split. A layer of mulch evens out those swings nicely.

Go easy with feeding. As a moderate feeder, beetroot usually manages in a well-prepared bed with no extra feed at all. Skip nitrogen-heavy fertilisers, they raise the nitrate content of the roots and reduce keeping quality. If you do feed, choose something potassium-rich, because beetroot really does need plenty of potassium. Fresh manure is completely unsuitable.

One point that often gets overlooked is boron. On acidic soils with a pH below 6, boron deficiency appears quickly, and you recognise it by heart rot and dry rot, meaning dark hollow patches inside the root. The better route is to raise the pH with a dose of lime rather than adding boron.

Keep the soil between the rows loose and the weeds short as long as the leaves have not yet covered the ground. That noticeably helps the roots swell.

Beetroot is tough overall, and if you keep to the rotation break you will have little trouble with most problems. The most common disease is Cercospora leaf spot (Cercospora beticola). It shows up as small round spots with a pale centre and a reddish-brown rim, first on the older leaves. In a heavy attack the foliage dies off, and without leaves the root stops growing. Ramularia leaf spot (Ramularia beticola) looks similar, its spots are larger and paler and it tends to appear in the cooler autumn.

Both fungi survive on plant debris in the soil. Clear the bed thoroughly in autumn and do not compost infected leaves. In mixed planting, distance from chard and spinach helps most, because these fungi travel short distances from plant to plant in splashing water. Water at the base rather than over the foliage.

Powdery mildew (Erysiphe betae) lays a greyish-white coating on the upper leaf surface and, unlike the leaf spots, appears in dry, warm weather. It does not kill cells but it costs yield.

The most important animal pest is the beet leaf miner (Pegomya betae). It lays white eggs on the underside of the leaves, and the larvae mine pale tunnels through the leaf tissue. Insect-proof mesh laid straight after sowing is the most effective protection; otherwise it is usually enough to pick off affected leaves and put them in the household waste.

Aphids sit in colonies on the heart leaves and pass on viruses such as beet mosaic virus. A strong jet of water helps at the start, and pot marigolds or Tagetes nearby attract hoverflies and lacewings, whose larvae finish off the aphids. Young plants also get chewed by flea beetles, which become active above all in dry weather.