UK crop guide
Beetroot is a succession crop. The RHS says to sow small batches from spring into mid-summer for roots from early summer to mid-autumn. Most are ready in 50 to 60 days, sometimes in as little as 40.
Each corky 'seed' is a cluster, so one station often gives several seedlings. That is useful if you want baby roots, and it is why multisowing in modules works so well.
Early sowings are worth starting in modules, especially in a colder garden. Sow one cluster 2.5cm deep in each cell. If several seedlings appear, thin to the strongest, unless you want a clump of baby roots, in which case sow up to four clusters and do not thin. Plant the clump out whole, without splitting it.
Wait until the soil is at least 7°C, from late March or April, and carry on until July. You can start in late February with a bolt-resistant variety if the row is covered with fleece or a cloche. On clay, which warms slowly, Gardeners' World suggests waiting a few weeks past late March before a direct sowing.
Sow 10cm apart, because the clusters are large enough to place one by one. Cover them with soil. For baby roots, sow two or three clusters together every 15cm and leave the clump. Rows on the March Gardeners' World sowing are about 30cm apart. Water the row if the ground is dry.
A container at least 40cm wide and deep will grow a useful crop. Beetroot is one of the better roots for pots.
Lift alternate plants once the roots are about golf-ball size, and leave the rest to grow. Stop at about cricket-ball size. Larger roots turn woody. Loosen them with a hand fork rather than pulling hard in heavy soil.
The leaves are edible too. Late roots can be stored for winter, so a July sowing is still worth making. Early summer to mid-autumn is the picking window from a full run of sowings.
A cold spell after an early sowing can make beetroot flower before the root swells. Use a bolt-resistant variety for late February and early March sowings, and cover the row. Later sowings, once the soil is properly warm, are less likely to bolt.
Left too long, the root toughens. The RHS suggests eating them from golf-ball size and not letting them get much bigger than a cricket ball.
Several seedlings from one cluster will all try to swell. Thin to one if you want a full-sized root, or deliberately keep a clump and eat them as babies. Do not pull the clump apart at planting time.
Kit for this crop, based on the method above.
A fine compost for modules and small pots. The RHS recommends peat-free mixes.
For crops started under cover. Deep pots suit peas, beans and sweetcorn.
For early sowings and for covering tender plants if a late frost is forecast.
Useful for warming a row before you sow, and for protecting early carrots and salads.
For lifting roots and potatoes without spearing the crop.
Variety and sowing date, so succession sowings do not get mixed up.
The thing you sow is a cluster of seeds stuck together. Thin to one plant for a full-sized root, or leave up to four and harvest them small. The RHS uses both methods.
Yes. July is the end of the outdoor window the RHS gives, and those roots are for late summer and autumn, with the last of them stored for winter.