Early varieties take up the least amount of space and form a clump about 45 centimetres wide. They can be set into a mixed border of annuals, perennials and vegetables, and their attractive flowers-in shades of white, pink, mauve, lavender, violet and purple-will add to the ornamental value of the bed until they mature around midsummer.
Four hundred and fifty grams of seed potatoes requires a 3.5-metre-long by 50- to 100-centimetre-wide row (allow one metre between rows) and will produce four to 11 kilograms of harvestable tubers. An unused, sunny strip of soil along a garage or garden path can also be used for a single row of mid- to late-season potato plants that remain in place until late-summer or autumn harvesting.
Potatoes can also be grown in raised borders and large containers (such as half-barrels), with sufficient soil volume to keep the tubers cool while maturing. Use a planting mix of equal parts potting soil and peat moss, and remember to hill up the sprouts twice as they grow. Container-grown potatoes require more frequent watering, and liquid fertilizer applications should be diluted to half-strength.
Pests and diseases
Symptoms sudden collapse of plants; water-soaked, grey patches Cause cool, wet weather Solution spray with organic Bordeaux mixture (copper fungicide)
Symptoms plants/branches gradually wilt; stems have brown interiors Cause verticillium wilt (a soil fungus) Solution pull out and destroy infected plants; grow crop in different location following year
Symptoms brown or black crusty patches on skin Cause scab disease (common in alkaline soil) Solution cosmetic damage only; tubers edible and can be stored
Symptoms misshapen tubers with knobs and cavities Cause alternating wet and dry conditions Solution avoid erratic watering and keep soil evenly moist; tubers edible and can be stored
Symptoms hollow hearts (too rapid growth causing internal cavities) Cause waterlogged soil Solution don't over-fertilize or overwater; keep soil evenly moist; tubers edible, but may not store well
Symptoms green-tinged skin (has formed toxic alkaloids) Cause exposure to sunlight Solution cut out toxic green sections (rest of tuber is edible); cover all tubers in ground with soil and mulch to keep light out; store in complete darkness
Symptoms leaves begin to roll upward; plant growth is stunted Cause leaf roll; virus carried in infected seed tubers and spread by aphids Solution plant certified seed tubers and remove any infected plants; early control of aphids with a pyrethrum spray will prevent spread of virus; tubers edible but plant less productive
Symptoms stunted growth, mottling and distortion of leaves with dark brown patches; foliage curls downward Cause mosaic viruses (A, Y and others) spread by aphids Solution spray plants with mineral oil to prevent virus from spreading; control aphids with a pyrethrum spray; tubers edible but plant less productive
Symptoms young sprout tips turn brown and die; hard, black spots form on developing tubers Cause black scurf/rhizoctonia canker (soil fungus) Solution plant healthy seed tubers; rotate planting bed if crop is scurfy; avoid planting in heavy, poorly drained soil; cover tubers with no more than five centimetres of soil; harvest promptly after vines have died; tubers edible
Symptoms seed tubers die before sprouts emerge from soil; plants that do emerge are stunted, and lower stems turn black, wilt and die Cause black leg bacterial infection Solution plant healthy seed potatoes when soil reaches 12˚C; too early planting in cold soil leads to rotting seed and infection; avoid wet sites
Symptoms water-soaked, grey patches on leaves; plants suddenly collapse Cause late blight fungus from cool, wet weather Solution spray with organic Bordeaux mixture (copper fungicide) at first sign of disease (repeat every seven to 10 days); remove foliage and stems from infected plants two weeks before harvest to prevent infection of tubers; tubers edible
Symptoms raised warts or sunken areas on tubers are white, soft and pulpy, then darken with decay Cause common scab, a soil-borne fungus that can live in soil for 30 years Solution plant certified seed potatoes and avoid using animal manures, which may carry the disease spores; rotate planting areas each year if severe; avoid drought stress; tubers edible