Radish (shown above)

(Raphanus sativus)

Climate

Suitable for all climate zones.

Planting

Sow seed any time of year except the coldest months. In the tropics and northern subtropics, radishes can be sown year-round. Soil must drain freely and be friable and fertile.

Growing

Keep moist but not overwet. Feed with liquid or soluble plant food every two weeks. Caterpillars and aphids are the main pests. Pick off and squash the former, spray the latter with soapy water or a pyrethrum insecticide.

To harvest, pull anytime from about a month after seedlings emerge. Don't let plants get too big - they are sweetest and most tender when young.

Beetroot

(Beta vulgaris)

Harvest beetroot two months after planting.

Climate

Grows in all climate zones.

Planting

Sow seed into soil that has had a small handful of lime dug in for each square metre. In hot and semi-arid climates, start sowing when soil temperatures exceed 7C. In tropical, dry subtropical and the warmer parts of humid subtropical and Mediterranean areas, sow in early autumn. In other climates, beetroot can be grown year round.

Growing

Thin seedlings to 3cm apart and later remove every second plant when they begin to crowd. Keep soil moist but don't feed the plants heavily. Cutworms destroy seedlings. Leaf miners damage leaves.

To harvest, pull roots any time after two months. Don't let the roots grow too big or they'll be woody.

Carrots

(Daucus carota)

Pick carrots whenever they're big enough to be eaten.

Climate

This cool season crop can grow in all zones.

Planting

Sow seed thinly. Do this any time except for the following: in the tropics and hot arid areas don't sow from mid-spring to early autumn; in Mediterranean and semi-arid areas don't sow in late autumn or early winter; and in temperate and cool temperate areas don't sow in autumn and winter. For a continuous supply, plant 5m rows every six weeks. Squat forms of carrots can be grown in containers.

Growing

Water seeds in well. Thin seedlings to 2cm apart. As they grow, harvest baby carrots so those left have room to develop. Don't overwater - let the soil dry out between waterings. Control carrot aphids at their first appearance. Root nematodes cause leaves to curl and turn red or yellow. Destroy affected carrots and treat the bed with nematicide.

To harvest, pull carrots whenever they are large enough to be eaten.

Celeriac

(Apium graveolens var. rapaceum)

Harvest by cutting the whole plant off at the ground, or remove outside stems as needed.

Climate

Best in cooler, temperate climates.

Planting

In cold areas, sow seed from spring to early summer; late winter to late summer in frost-free areas. Sow into containers or trays and then transplant seedlings into small individual pots. When big enough, plant into fertile, free-draining soil that contains plenty of rotted manure and a ration of complete plant food.

Growing

Keep moist - water daily in summer. After planting out, feed every three weeks with soluble or liquid fertiliser. Slugs and snails will damage stems and a leaf-spotting fungus may attack the plant. It can be controlled with fungicide.

To harvest, cut the whole plant at ground level or remove outside stems as needed.

Parsnip

(Pastinaca sativa)

Harvest parsnips after 4-5 months.

Climate

Suitable for all climate zones.

Planting

Sow seed in autumn and winter in tropical and northern subtropical areas, from late winter to autumn in mild zones and from spring to summer in cooler places. Soil must be dug over but not very rich - plant after another crop has been harvested.

Growing

Water deeply but not too frequently to encourage long roots. Mulch plants in summer to keep soil cool. Aphids can cause leaves to distort - spray with soapy water or a mild insecticide.

They're ready to harvest after four to five months. Lift the whole plant using a garden fork.

Potato

(Solanum tuberosum)

Potatoes take 3-4 months to mature.

Climate

Grows in all zones.

Planting

Buy only certified, disease-free seed potatoes from nurseries. Plant each 10cm deep into well-drained, fertile but not overly rich soil. Cover with soil, then water them in. Start with six plants. Potatoes take three to four months to mature. In hot areas, plant after the extreme heat of summer has passed, and in cold areas after frosts have finished in spring.

Growing

Keep moist but not wet, and as the plants grow, mound up soil around the stems so no tubers are exposed to light. Remove weeds and stop watering as soon as the plants begin to die. The potato tuber moth leaves wiggly marks on the foliage and should be sprayed at first appearance. Aphids are another common pest and in humid weather leaf spotting or blighting diseases may occur. Control these with fungicides.

To harvest, dig potatoes after the top growth has died.

Swedes

(Brassica napus var. napobrassica)

Harvest swedes 3-4 months after the seedlings emerge.

Climate

Best in cooler areas, such as temperate and cool temperate climates and the cooler parts of humid subtropical, Mediterranean and semi-arid zones. Possible in other areas as a cool-season crop.

Planting

Sow seed in autumn. In cool temperate areas and cold parts of temperate areas, sow midsummer and again at the end of winter. Sow or thin to 12cm apart. Soil that has grown a previous crop is ideal for swedes (but not if that crop was cabbages, broccoli or brussels sprouts).

Growing

Don't allow swedes to dry out. Apply complete plant food a month after planting. Keep weeds down and don't hill soil around the exposed top of the root. Caterpillars and aphids are the main pests. Both can be controlled with pyrethrum-based insecticides. To harvest, pull the whole root before it gets too big and woody.

Plants are usually ready for harvest three to four months after seedlings emerge.

Sweet potato

(Ipomoea batatas)

Harvest sweet potatoes 20 weeks after planting.

Climate

Needs a long, hot, sunny summer. Not suitable for cool temperate areas.

Planting

Grow from cuttings or from shoots from a bought tuber. Plant the cuttings or shoots very shallowly into wide ridges of soil that has grown a previous crop. Space 30cm apart and water in well. Sweet potato plants run over the ground (2m or more in all directions) and all that space must be weed-free. In tropical and dry subtropical areas, sweet potatoes are started just after the wet season finishes. In all other areas, start them in middle to late spring. Try planting five plants to begin with.

Growing

Keep moist. If planted into fertile soil, no feeding is needed. Sweet potato is usually trouble-free in the home garden but don't plant it in the same spot twice.

Harvest when the vine begins to die back (about 20 weeks after planting). Be careful, the tubers damage easily.

Turnip

(Brassica rapa)

Pull turnips 2-3 months after you see the first seedlings.

Climate

Best in cooler zones - temperate and cool-temperate areas and the cooler parts of humid subtropical, Mediterranean and semi-arid zones. Possible in other areas as a cool-season crop.

Planting

Sow seed in autumn. In cool-temperate and cold parts of temperate areas, sow midsummer and again at the end of winter. Sow or thin to 10cm apart. Soil that has grown a previous crop is ideal for turnips (but not if that crop was cabbages, broccoli or brussels sprouts).

Growing

Don't allow the seedlings or developing vegetables to dry out. Apply complete plant food a month after planting. Keep weeds down and don't hill soil around the exposed top of the root. Caterpillars and aphids are the main pests: control with pyrethrum-based insecticides.

To harvest, pull the whole root before it gets too big and woody. Plants are usually ready for harvest two to three months after seedlings emerge.

Source: Gardening: A Commonsense Guide (Murdoch Books)