Agriculture Reference
In-Depth Information
In the polytunnel it enjoys a longer season than outdoors but, most importantly,
it grows to maturity in seven or eight weeks, making it an ideal catch crop
between slower-growing plants, such as tomatoes or aubergines, at the begin-
ning and the end of the season.
Preparation
Kohlrabi needs a rich, moist soil but does not root deeply. A month or two before
sowing, top dress the bed with compost, fork it gently into the top few inches and
water in well. A week or so later, check the pH of the soil and correct it with a
dusting of lime if necessary - it should ideally be 6.5 to 7.0 but certainly no lower
than 6.
Sowing
Sow thinly 1cm deep in drills 20cm apart, thinning the plants to around 10cm
apart as soon as they are large enough to handle. Keep the soil moist but not
waterlogged, and protect from pests. If slugs are a problem in your tunnel don't
sow direct; use 3cm modules and transplant to 10cm apart in the rows once the
plants have five leaves.
To maintain a continuous supply of kohlrabi, sow every three or four weeks from
early spring to early autumn, but be aware that it prefers cool conditions and
grows quite slowly during the summer, so it may be best not to sow any between
May and August.
Growing
As the plants begin to plump up, harvest every other plant as it reaches golf-ball
size and leave the others to grow on. As with many vegetables, kohlrabi is at its
finest and tenderest if harvested small. Over winter, plants will need protection
with fleece to cope with temperatures below -3°C.
Harvesting and storage
Take the remaining plants by the time they reach the size of a tennis ball, as they
have a tendency towards woodiness as they get larger. Lift the whole plan, or, if
you are growing between other plants and don't wish to disturb their roots, just
cut the stem at ground level. If you are not using it immediately the bulb keeps
better with the roots and leaves removed; the leaves are edible and good, and
should be treated like kale. Once trimmed, kohlrabi bulbs will keep for a month
or more in a sealed bag in the fridge, but autumn or winter harvests will store
even better in a cool garage or outbuilding, where they should be set out on racks
to allow good air circulation.
Problems
Kohlrabi matures so quickly that once plants are established they rarely have
any problems, but keep an eye on them and remove any caterpillars or slugs.
