Although it may not yet feel like it, autumn is on its way and root vegetables, including carrots, beetroot, onions, turnips and radishes, prefer the cooler growing conditions.
Most seed packets indicate that carrots, beetroot and radishes can be sown throughout the year, but in very hot regions, or hot gardens, their performance can be disappointing. If this has caused you to give up on planting them, why not try once more, during autumn? Experienced gardeners claim that autumn-planted carrots are much sweeter, radishes crisper and beetroot better developed.
Because their growth is downward, root vegetables take up very little room but reward with good yields (this is especially true of carrots); this makes them excellent crops for small gardens. Each vegetable has its individual quirks, but the same basic growing conditions apply:
• A good depth of soil (30 cm) is necessary, worked over well, the clods broken down and raked free of sticks and stones that could interfere with the development of the roots.
• Light soil, on the sandy side, is best for root vegetables. Heavy, clay-like garden soil isn’t really suitable as it inhibits root and bulb formation. Make heavy soil more friable by digging in lots of compost. Another excellent soil conditioner is compressed palm peat. It comes in brick form and swells to five times the amount when soaked in hot water.
• Root crops don’t like soil that contains manure or fresh compost as this encourages the tops to develop at the expense of the roots. Carrots are particularly sensitive to high levels of manure and fresh compost; it may damage the carrot and cause it to split. A good idea is to plant root crops in beds that were previously enriched and planted with tomatoes, potatoes or brassicas (such as cabbages or broccoli). In this case all you need add is bone meal or superphosphate.
• They all do best in a sunny position but beetroot can grow in a position that receives lots of good light but not necessarily sun.
• Germination rates can vary and the soil should be kept moist, but not sodden as you wait for germination. If it is still hot, water the seed beds once a day.
• Plants need to be thinned out to the spacing recommended on the seed packet so that the roots have space to develop. If the tops of carrots, beetroot, turnips and radish are removed they will last for at least two weeks in a refrigerator. Onions have an even longer shelf life but need to be dried first in a cool, dark place. As a bonus, the tender leaves of beetroot and turnips can be eaten as spinach, and young beetroot leaves can be used in salads as well.
Quick tips for growing carrots
• Of all the root crops carrots are the most particular about the soil, which needs to be deep and on the sandy side.
• Carrot seed is very fine and should be sown where the carrots are to grow. Germination takes about two weeks, during which time the soil should be kept moist.
• Try sowing radish seed with the carrots. The radishes germinate quickly and shade the carrot seed. By the time the carrots are seedlings the radishes will have been harvested.
• Start thinning out when the first two or three true leaves develop, leaving the seedlings 1 cm apart to begin with. The last thinning out should leave the plants 3 to 5 cm apart.
• Water regularly and don’t let the soil dry out.
• Keep the shoulders of the carrots covered to prevent them from turning green, which gives the carrot a bitter taste.
Quick tips for growing beetroot
• Sow seeds 3 cm apart, in full sun, directly into the soil about 2 to 3 cm deep in rows 30 cm apart.
• Thin out the seedlings to about 5 cm apart when they are about 5 cm high, otherwise the root becomes woody. Keep on thinning out until the final spacing is about 10 to 15 cm apart.
• An easy way of thinning out seedlings is to use kitchen scissors and snip off the unwanted seedlings at ground level.
• Seedlings that sprawl and don’t grow upright may have been planted too shallowly or watering has washed some of the soil away, leaving the roots too close to the surface. It could also be that they are not getting enough sunlight.
• Drawing the soil up around the plants after the final thinning will help to support them.
• For maximum flavour harvest when the roots are 5 to 10 cm in diameter. Twist off the leafy tops and try to avoid damaging the tap root beneath the bulbous portion (to prevent ‘bleeding’).
• Poor quality or woody beetroots can be the result of heavy soil, plants growing too close together or hot, dry weather and not enough water during the root formation period.
Quick tips for growing onions
• Sow seed directly into the soil or in seed trays. Seedlings should be ready for transplanting after eight weeks. Discard seedlings that have started swelling at the base. Roots and leaves can be lightly trimmed.
• Water regularly during the growing period, especially during the first five to six weeks after germination. Only reduce watering once the bulb is well developed so that the plants start to dry off.
• Thrips is a major pest and can be controlled by spraying preventively with an organic insecticide (thrips is invisible in its early stages).
• When the green tops fall over it is time to harvest the onions; thereafter let them dry off in a dark, cool, well ventilated area.
• Ideal onion varieties for autumn sowing are Texas Grano 502 PRR, Hanna, Shahar and San, as they require medium to short day lengths, as do Sivan and Red Creole (two red onion varieties).
Quick tips for growing radishes
• Sow radishes where they are to grow. Seed can be broadcast or sown in shallow drills. They also do very well in window boxes and containers.
• Plants should be thinned out to a final spacing of 3 cm between plants.
• Harvest three to five weeks after sowing. Radishes left in the ground too long become large, pithy and too peppery.
Quick tips for growing turnips
• Turnips like firm soil so tramp it down lightly after it has been dug over.
• Sow seed in shallow drills where the turnips are to grow. Cover with 1 to 2 cm of light soil, firmed down gently and watered carefully.
• Turnips germinate quickly – within 3 to 4 days if the soil is kept moist.
• Start thinning out two weeks after germination and regularly after that until the final spacing is 6 to 8 cm apart. Water the bed before thinning out or snip off the seedlings at ground level. Draw soil up around the plants to support them.
• Turnips can suffer from a boron deficiency, indicated by the yellowing of leaf margins, so apply trace elements if that occurs.
• For a good crop, turnips must grow rapidly and should be ready for harvest within 8 to 10 weeks, at which point the bulbs will be 5 to 6 cm in diameter.
Information supplied by Di-Di Hoffman
of Bouquet Garni Nursery, potted herb
grower and marketer. Visit Di-Di at www.
gofoodgardening.com or phone Bouquet
Garni on 012 8081044.