The potato (Solanum tuberosum) is one of the world's most important food crops and a staple in gardens and kitchens across the globe. A member of the nightshade family, it is a close relative of the tomato, aubergine, and chilli.

Origins

Originating in the Andes, where it was cultivated for thousands of years, the potato spread worldwide and became central to the diet of many cultures. Today it ranks among the top food crops globally, valued for its high yield, nutritional density, and adaptability to a wide range of climates.

Types and Varieties

Potatoes are broadly divided by their maturity date:

• First Earlies (New Potatoes): Quick to mature, with thin, waxy skins and a sweet, buttery flavour. Best eaten fresh.
• Second Earlies: A middle ground — slightly larger with good flavour.
• Maincrops: Large, starchy tubers ideal for baking, roasting, mashing, and long-term storage.

Culinary Uses

Few vegetables are more versatile. Potatoes can be boiled, baked, roasted, fried, steamed, or mashed. Their flesh ranges from white to golden-yellow, and some heritage varieties offer striking purple or blue-fleshed tubers with a rich, nutty flavour.

Nutritional Value

Potatoes are a good source of vitamin C, potassium, vitamin B6, and dietary fibre, especially when eaten with the skin on.

How To Grow

Obtaining Seed Potatoes

Always start with certified, disease-free seed potatoes purchased from a reputable supplier. Avoid using supermarket potatoes, which are often treated with sprout inhibitors and may carry disease.

Chitting (Pre-Sprouting)

Before planting, encourage your seed potatoes to sprout:

1. Place them in a tray or egg carton with the 'rose end' (the end with the most eyes) facing upward.
2. Keep them in a cool, bright, frost-free location.
3. After 4–6 weeks, short, sturdy green or purple sprouts about 2–3 cm long will form. The potatoes are then ready to plant.

Chitting gives plants a head start, especially useful in cooler climates with shorter growing seasons.

Planting

• Soil Preparation: Potatoes prefer a loose, well-drained, slightly acidic soil. Dig in plenty of well-rotted compost or manure before planting.
• Depth: Plant tubers approximately 10–15 cm deep.
• Spacing: Space tubers 30 cm apart within rows, with 60–75 cm between rows to allow for earthing up.
• Containers: Potatoes grow very well in large pots or purpose-made grow bags. Start with 10–15 cm of compost at the base, add the tubers, then cover.

Earthing Up

As shoots reach 15–20 cm tall, mound soil or compost around the stems, leaving only the top leaves exposed. Repeat as the plant grows. This:

• Prevents tubers near the surface from turning green (green tubers contain solanine and are not edible)
• Encourages more tubers to form along the buried stems
• Provides some frost protection to emerging shoots

Watering and Feeding

• Keep soil consistently moist, especially from flowering onwards when tubers are actively bulking up.
• Avoid waterlogging, which encourages rot.
• In containers, a liquid feed high in potassium every 1–2 weeks once plants are established will boost yields.

Harvesting

When to Harvest

The timing of your harvest depends on the variety type and what you intend to do with the potatoes:

Reading the Signs

• Flowering: When the plant flowers, gently scrape away a little soil to check tuber size. If they are marble-sized, you can wait a little longer or harvest as very small new potatoes.
• Die-back: For maincrop varieties, wait until the entire foliage has yellowed and collapsed before harvesting. After die-back, wait a further 10 days before lifting — this allows the skins to set (harden), which greatly improves storage life.

Digging Up

• Use a garden fork rather than a spade to reduce the risk of cutting tubers.
• Insert the fork well away from the base of the plant (30 cm or more) and lever upward to bring the whole root ball to the surface.
• Search through the loosened soil carefully — small potatoes hide easily and left-behind tubers will regrow as unwanted volunteers next season.
• Containers: Simply tip the container onto a sheet or lawn and sift through the growing medium by hand for a clean, damage-free harvest.

Curing and Storage

• Brush off excess soil but do not wash potatoes you intend to store.
• Lay them in a single layer in a dark, cool, well-ventilated space for 7–10 days to cure the skin.
• Store in hessian (burlap) or paper sacks — never plastic, which traps moisture and causes rot.
• Check stored potatoes regularly and remove any showing signs of softness or rot.

Important Safety Note

Discard any tubers that have turned green. Green skin and flesh indicates the presence of solanine, a naturally occurring toxin that can cause illness if consumed in significant quantities.

Common Problems

Common Pests

Slugs and Snails

One of the most damaging potato pests. Slugs tunnel into tubers underground, leaving holes and creating entry points for rot. Encourage natural predators (hedgehogs, frogs, ground beetles), use copper barriers around containers, and apply biological controls (nematodes) to the soil in warm, moist conditions.

Wireworm

The larvae of click beetles, wireworms tunnel into tubers leaving thin, cylindrical channels. Most troublesome in soils recently converted from lawn. Improving drainage and crop rotation help reduce populations over time.

Aphids

Greenfly and blackfly can colonise potato foliage and, more importantly, transmit viral diseases. Remove colonies by hand or with a strong spray of water; encourage natural predators such as ladybirds (ladybugs) and lacewings.

Colorado Potato Beetle

A yellow-and-black striped beetle and its larvae that can rapidly defoliate plants. Check the undersides of leaves for orange egg clusters and remove by hand. Rotate crops and use row covers where this pest is a concern.

Common Diseases

Potato Blight (Phytophthora infestans)

The most serious potato disease. Brown, water-soaked patches appear on leaves and stems, spreading rapidly in warm, humid conditions. Tubers develop a reddish-brown rot beneath the skin. Prevention is key:

• Choose blight-resistant varieties
• Avoid wetting foliage when watering
• Apply copper-based fungicide preventatively in high-risk conditions
• Remove and destroy (do not compost) all infected material

Potato Scab (Streptomyces scabies)

Rough, corky patches on the tuber skin. Caused by alkaline soil conditions. Reduce risk by maintaining a slightly acidic soil pH (5.0–6.5) and watering consistently during tuber development.

Blackleg

A bacterial disease causing blackening of the stem base and yellowing of foliage. Plants may collapse entirely. Remove and destroy affected plants; do not save tubers from infected plants as seed potatoes.

Virus Diseases

Mosaic virus and leaf roll virus cause mottled, distorted, or rolling foliage and reduce yields significantly. Always use certified virus-free seed potatoes and control aphid populations to limit spread.

General Prevention

• Crop rotation is the single most effective preventative measure — avoid growing potatoes (or other nightshades) in the same bed more than once every 3–4 years.
• Good hygiene: Remove all plant debris at the end of the season.
• Certified seed potatoes: Always plant certified, disease-free stock rather than saving your own tubers from potentially infected plants.