Knol kohl or Kohlrabi is one of the many vegetables of European origin that have crept into our regular diet. ‘Kohl' in German means cabbage and ‘rabi' refers to turnip.
Belonging to the Brassica (mustard, cabbage, and so on) family, the edible part of the vegetable is the stem, which looks like a turnip albeit with cabbage-like leaves. It is tolerant of a wide range of climatic conditions, but prefers cool temperature. June is a good time to start cultivating. Of the several varieties, all of which are white inside, the commonly grown ones in India are white Vienna with light green skin and purple Vienna, with a purplish skin. The heat tolerant green variety is grown more in the south.
Like other Brassica plants, knol kohl needs exposure to sun and well-drained soil rich in organic matter. To sow directly, dig the soil to about 25 cm depth, fill 5 cm of it with organic compost, mix well and leave for a few days.
Mark out shallow drills 30 cm apart. Sow three seeds at intervals of 15 cm. When the seedlings are 3 cm high, thin out to one per hole, also 15 cm apart. If sowed in seed trays, they can be transplanted when the seedlings have two to three true leaves.
Before transplanting, water the seedlings thoroughly so that they can be lifted without damaging the roots. Plant the seedlings with a hand fork; water and firm the soil around the roots.
Just right for picking
Keep the soil evenly moist as the vegetable becomes woody if grown without water. Side dress with fertilizer midseason, when the plant will push itself out of the ground with the swollen stem sitting on the surface. In 60 to 70 days, well-nourished plants develop stems of around 5 cm diameter. At this stage, the vegetable is crisp and tasty. If allowed to grow too big, they become unpalatable. The leaves and leaf stalk are tasty and can be cooked or used in salad. But if the plant is defoliated (has its leaves plucked) frequently, stem development is slowed down.
This plant suffers from the same pests as cabbage, which chew through the leaves. Pick out the worms or use neem and soap spray. A few leaves eaten by worms do not affect the vegetable.
The mildly sweet knol kohl is rich in phytochemicals, vitamins C, A and B complex, and minerals. Tender knol kohl is excellent in salad and gravies. It is tastiest in combination with mutton or prawns.