Soil for root crops should be light with good drainage. If your soil is heavy, consider shorter-growing cultivars when purchasing your seeds. Also, be sure to incorporate extra sand and zeolite to improve the soil’s texture. Zeolite is a 100 per cent natural mineral used for soil conditioning. This crushed volcanic rock breaks up clay soils and allows air and water to flow more freely. Once worked into the soil it lasts for years.
Drainage is also improved by adding manure and compost. They also help the soil to retain nutrients, and they get the beneficial organisms going. When applying manure to areas that will grow root crops, however, be sure that the manure is fully composted and go easy on the applications. Fresh manure will burn the roots of many plants and it contains high levels of nitrogen that will produce hairy roots and diminish flavour.
Adding fertilizers, other than nitrogen, improves flavour, helps them resist pests and diseases and improves their storage life. Prior to planting your seeds, apply glacial rock dust, an excellent source of trace elements, to the soil bed. Be generous with potassium and phosphorus but sparing with nitrogen. Continue to fertilize every two weeks with liquid fish fertilizer or kelp spray.
Daily deep watering is critical to the development of root vegetables. During periods of very hot dry weather it may be necessary to water twice a day to cool the soil down; very warm soil produces roots with less flavour. Lastly, water just before harvest – this makes the soil softer and allows the roots to be pulled or dug easier.
Sheena’s Top 10 Underground Crops
Beet – ‘Kestral’: Sweet with dark red colour.
Carrot – ‘Minicor’: Crunchy texture and unbeatable flavour.
Celeriac – ‘Mentor’: A cultivar of celery that develops an edible, swollen stem base. It has a mild parsley/celery taste and is tender and crisp.
Jerusalem Artichoke: This productive and disease- and pest-resistant artichoke produces knobbly, tuberous rhizomes with a nut-like flavour and the texture of a water chestnut. Can be eaten raw in salads or cooked as you would potatoes.
Onion – ‘Copra’: The best onion for production and storage.
Parsley – ‘Hamburg’: A form of true parsley, this plant produces a thick, fleshy, parsnip-like root that tastes like a blend of celery and parsley. The foliage can be used in cooking.
Potato – ‘Purple Peruvian’: Very productive fingerling potato. This potato retains its deep purple skin and flesh colour when cooked. Delicious flavour, disease resistant and an excellent keeper.
Radish – ‘Daikon’: This sweet, juicy, white Japanese radish can reach 75 cm (30 in.) easily, so dig the soil deep. Excellent raw or steamed.
Radish – ‘Easter Egg’: This blend has all the radish colours; they grow at about the same rate and are all white inside, but the skin colours are white, red or purple.
Shallot – ‘Dutch Yellow’: An excellent keeper, this 10-cm (2-in.) yellow-fleshed shallot has a soft garlic flavour.