Vegetable production: Growing beetroot successfully

This popular vegetable is a good choice. Beetroot is fairly easy to grow and produces a good yield.

Beetroot is a close relative of Swiss chard and sugar beet, and has many health benefits. The young leaves are tasty, a good source of vitamin A and can be prepared in the same way as spinach. The beets are rich in vitamin C.

Beetroot is a cool weather crop, but the hybrid (F1) cultivars available for summer production offer many advantages. The seed is expensive, but these beets are worth growing because they are better quality, more adaptable to extreme high temperatures and so are more uniform in shape, produce greater yields and have better internal colour. Hybrids also taste better, especially out of season.

CLIMATE

Beetroot is usually grown in cool regions or during the cooler seasons in warm areas.
The growing period varies from 8 to 11 weeks in favourable climatic conditions.
In hot weather the quality is adversely affected, which is shown by the alternate white and red rings when the beets are sliced.
High-quality beets are characterised by a high sugar content and dark internal colour.
The best planting times for beetroot are spring and autumn.
The optimum temperature for growth is between 15°C and 20°C.
Beets are not particularly sensitive to heat, as long as there is enough moisture in the soil. Although tolerant to cold, they grow extremely slowly in winter.
Leaves may be damaged and growth retarded if there is frost before harvesting.
Cold weather might delay maturity and the tops tend to be smaller.
Direct sowing can result in good germination at temperatures between 6°C and 24ºC.
On hot sunny days, high temperatures that develop at, or just below, the soil surface might injure young plants badly, or kill them.
High temperatures for long periods may not only retard growth and depress yield, but could also cause an undesirable strong flavour, concentric rings and a coarse texture.

SOIL REQUIREMENTS

Sandy to deep, well-drained sandy loam or silt loam, high in organic matter, is recommended. Cloddy, stony, poor or very shallow soils are not suitable.
Uniform soil moisture is essential for good quality.
If the soil is compacted or the clay content is very high, roots are likely to be deformed and to develop a tough texture that reduces quality.
Crops thrive in deep, rich sandy loam, with a pH of between 6 and 6.5 (but not below).

Also read:
Do it yourself: Making your own basic soil pH test
How to increase the pH of your soil
How to lower the pH of your soil

RAISED BEDS

Raised beds can increase the effective depth of soil, allowing it to drain better, concentrate topsoil around the root zone, and provide more oxygen for healthy root development.
Aeration is better, and disease, infection and the incidence of damping off are all reduced.
Raised beds are truly beneficial if soil is heavy and/or poorly drained. Harvesting is also easier.
Raised beds should be 1 m to 1.2 m wide with 50 cm between them.
If you’re making them by hand, mark the area with twine, then use a spade and a rake to make the beds.
Large-scale farmers obviously use special equipment to make beds.
If you have 1.2 m wide beds, 6 rows or furrows that are 2 cm deep would be good spacing. Start the furrows 10 cm from the side of the seedbed and allow 20 cm between rows.
Sow the seed 2 cm to 3 cm apart and cover the furrows firmly with the soil from the furrows.

DIRECT SOWING

It is essential that farmers buy quality seed that has a good germination percentage.
It is very important to establish a fine, level seedbed when sowing the seed and to irrigate lightly a day before sowing.
If done by hand, try to sow the seed evenly in the furrow about 3 cm to 4 cm apart.
Do not sow too densely – that makes later thinning of the plants uncomfortable.
Thin plants to 5 cm to 9 cm apart in the rows, depending on the size of beets needed for a specific market.
If possible, sow seeds when the weather is cloudy.

TRANSPLANTING

More than 90% of beetroot producers sow the seed directly in the soil, but seed can also be sown in seedbeds and transplanted.

Seed trays or other containers can also be used to raise seedlings but this is expensive because of the high cost (about 450 000 plants are needed to establish 1 ha).

MULCHING

Mulching can protect emerging seed from burning and keep the top soil layer moist and cool. Mulching materials include straw, corn cobs, sawdust, sunflower seeds, peanut shells, grass, grass clippings, newspapers and household waste.

Good mulch must be inexpensive, available and easy to handle. It must also be stable, so that it will not easily wash or blow away.
Remember that it’s the temperature of the soil, not of the air, that controls seed germination so it is best to wait for soil temperature to rise before sowing seed.
In summer, mulch has a cooling effect on the root system.
A good layer of mulch can reduce evaporation from the soil surface by as much as 70%.

FERTILISING

A soil analysis or test is the most accurate guide to fertiliser requirements.
Recommended soil sampling procedures should be followed in order to estimate fertiliser needs, and good management practices are very important if optimum fertiliser responses to beets are to be realised.
Top or side dressings of nitrogen should be applied at about 100 kg/ha or (10 g/m²) at the three-leaf stage, about 3 weeks after emergence, and 100 kg/ha 3 weeks later.
Potassium levels should be kept fairly high. The second top dressing can be1:0:1 or potassium nitrate if K levels are low.
Beetroot prefers well-drained soil, well-supplied with lime and potash.
Heavy soils usually are not so likely to run short of potash.
A lack of phosphorus or nitrogen will stunt growth and produce a deep red colour.
When grown extensively under irrigation, beets can tolerate high salt concentrations.
Beetroot are sensitive to high acidity and low boron levels.
They are, in fact, a good indicator for boron deficiency: blackened areas and cracked roots are usually signs and, when cooked, there are black spots throughout the tissue and the beets taste bitter.

IRRIGATING

Always irrigate carefully and, early in the season, take care not to irrigate too much.
Waterlogging can turn leaves red and plants may stop growing for a while.
As a general guide, apply 300 mm to 350 mm water throughout the growing season, starting off with 20 mm in the first week and 40 mm every week thereafter.
Irrigation is especially important in the early stages of plant development and during root development.
When sowing beetroot, keep the soil damp, lightly irrigating often to keep the surface cool, especially in warm weather.
The growth points of emerging seed are very sensitive to hot soil conditions, so during long spells of hot, sunny weather, give about 8 mm water per day.
On cold winter days, about 2 mm of water is needed.
It is critical to irrigate the field in the last half of the growing season.
Water shortages at this time could have the greatest negative influence on yields.
During this period irrigate early in the day so that leaves can dry off and prevent diseases developing.

HARVESTING

Soil should be slightly moist before cutting or pulling beets.
If the soil is too dry, roots may be difficult to clean and the rate of top breakage may be too high.
For best flavour and tenderness, harvesting should begin when roots are 3 cm to 4 cm in diameter.
Most beets grown commercially, however, are harvested when they are fully mature to obtain the highest yields.
Handle beets carefully after harvesting to avoid damaging the roots.
Damage reduces shelf life and increases the chances of decay and disease.
Fresh market beets can be stored for 10 to 14 days, at 0°C and 98% to 100% relative humidity.

This article was written by Piet Stork and first appeared in Farming SA.