How to grow potatoes — chitting to harvest guide

How to grow potatoes — chitting to harvest, by container or bed

Potatoes are the highest-yielding crop most home gardeners will ever grow — a single seed potato returns 5-10 tubers — and one of the most forgiving, as long as you respect two rules: keep the developing tubers covered (light turns them green and toxic), and don't plant supermarket potatoes. This is the full year-one playbook: chitting, the three growing methods, earthing up, the blight watch, and harvest timing by potato type. Potatoes rotate well before alliums, so many growers follow a potato bed with onions or garlic the next season.

Track your potato crop: Add your variety and zip code or postcode to Growli and the app sets reminders tied to your local frost date — when to start chitting, when to plant, when to earth up, and when each type is ready to lift.

First earlies, second earlies, and maincrop

Potatoes are sorted into groups by how long they take from planting to harvest. Pick a group before you pick a variety — it decides your planting date and your harvest window.

First and second earlies are dug fresh and eaten within days. Maincrop potatoes are left to mature, cured, and stored for months — these are the ones that fill a winter pantry.

Choose a variety

US varieties

• Yukon Gold — yellow-fleshed, all-purpose, early-to-mid season, an excellent keeper. The reliable beginner pick.
• Red Pontiac — red-skinned, firm, good for boiling and salads; adapts well to both Southern and Northern gardens (about 80-100 days).
• Kennebec — high-yielding white maincrop, good disease tolerance, classic for fries.
• Russet Burbank — the dominant US commercial potato; high-starch, late maincrop, the classic baker — needs a long season.
• Adirondack Blue — blue-purple skin and flesh, novelty variety with good antioxidant content.

UK varieties (RHS Award of Garden Merit verified)

These all hold the RHS Award of Garden Merit (AGM), meaning they performed reliably in RHS trials:

• Charlotte AGM — the benchmark second-early salad potato; pear-shaped, waxy, yellow.
• Maris Piper AGM — the UK's favourite maincrop; floury, the standard chipping potato.
• Desiree AGM — red-skinned maincrop, drought-tolerant, stores well.
• Pink Fir Apple AGM — knobbly waxy salad maincrop with a nutty flavour.
• Sarpo Mira AGM — red-skinned maincrop with notably strong blight and slug resistance — the variety to grow in a wet UK summer.

"Rocket" is a popular UK first early but is not currently on the RHS AGM list; "King Edward" is a long-standing favourite maincrop but is also not currently AGM-listed — both still grow well, they just have not been through a recent trial. For AGM picks, Maris Piper, Desiree, Charlotte, and Sarpo Mira are the safe bets.

Chitting — the head start

Chitting means sprouting seed potatoes indoors before planting so they grow away faster once in the ground. It is most worthwhile for first earlies.

1. Buy certified seed potatoes from a nursery or seed company — never supermarket potatoes. Shop-bought tubers are often treated with sprout inhibitors and may carry disease.
2. 4-6 weeks before your planting date, stand the tubers eyes-up in an egg box or seed tray.
3. Put them somewhere cool (about 50°F / 10°C), bright but out of direct sun. A bright windowsill in an unheated room is ideal.
4. Wait for short, sturdy, green-purple sprouts about 1 inch (2-3 cm) long. Long pale spindly sprouts mean it was too warm and too dark — rub the weakest off and keep the 2-3 strongest.

Chitting also helps the plant outrun early late blight infection because the crop advances more quickly. Maincrop potatoes do not strictly need chitting but it does no harm.

Soil and site

• Full sun — 6+ hours direct.
• Loose, free-draining soil rich in organic matter. Heavy clay needs compost or a raised bed; compacted soil produces small, deformed tubers.
• Slightly acidic pH — 5.0-6.0. Potatoes prefer acidic soil; high pH encourages scab. Check yours with our soil pH guide before adding lime anywhere near the potato bed.
• No fresh manure and don't follow tomatoes, peppers, or eggplant (shared blight and disease) — see companion planting for a rotation that works.

The three growing methods

1. Trench / ridge (the traditional method)

1. Dig a trench 6 inches deep.
2. Place seed potatoes (chitted side up) 12 inches apart for earlies, 15 inches for maincrop, in rows 24-30 inches apart.
3. Cover with 4 inches of soil.
4. Earth up (see below) as shoots grow.

2. Container / grow bag

The best method for patios and small spaces — and our container vegetable gardening guide covers pot sizing in detail.

1. Use a 10-15 gallon (40-60 L) grow bag or bin with drainage holes.
2. Add 4 inches of potting mix, set 2-3 seed potatoes on it, cover with 4 inches more mix.
3. As stems grow, keep adding mix until the bag is full (this is container "earthing up").
4. Water consistently — containers dry fast and inconsistent water causes hollow, cracked tubers.

3. No-dig (under mulch / straw)

1. Lay seed potatoes on top of weed-free soil or compost.
2. Cover with 6-8 inches of loose straw or mulch.
3. Add more mulch as stems grow to keep tubers in the dark.
4. Harvest by pulling back the mulch — no digging, almost no damaged tubers.

Earthing up — the non-negotiable step

As the green stems reach 8 inches tall, draw soil (or mulch, or more compost) up around them, leaving just the top few inches of leaves exposed. Repeat every 2-3 weeks until the ridge is 10-12 inches high.

Earthing up does three things:

• Stops tubers greening. Potatoes exposed to light turn green and develop solanine, a toxic glycoalkaloid (see the warning below). This is the single most important reason to earth up.
• Increases yield — more buried stem means more tubers.
• Reduces blight tuber infection — spores washed off the leaves are filtered by the soil before reaching tubers.

Watering and feeding

• Most critical period: from flowering onward, when tubers bulk up. Deep, consistent watering (about 1-2 inches per week) prevents hollow centres and growth cracks.
• Inconsistent watering (dry then drenched) causes "knobbly" tubers and growth cracking.
• A balanced feed at planting is plenty for earlies; maincrop benefits from a higher-potassium feed once tubers start forming. Don't overdo nitrogen — it grows lush leaves at the expense of tubers.

Pest and disease watch

• Late blight (Phytophthora infestans) — the big one, especially in wet UK summers. Brown-black blotches on leaves with a pale halo, then collapse; spores wash down to rot tubers. Conditions: night temps 50-60°F, day 60-70°F with leaf wetness. Manage by chitting (faster crop), watering at the base in the morning, earthing up well, choosing resistant varieties (Sarpo Mira), and cutting and removing all foliage at the first sign so tubers stay clean underground. Note this is late blight — distinct from powdery mildew, a dry-weather fungus that does not affect potatoes the same way.
• Colorado potato beetle (US) — striped beetles and red larvae strip foliage. Hand-pick; check undersides of leaves for orange egg clusters.
• Scab — corky patches on skin from alkaline or dry soil. Cosmetic only; keep pH acidic and soil consistently moist during tuber set.
• Slugs (UK) — tunnel into tubers in wet soil. Harvest maincrop promptly; choose slug-resistant varieties.

Harvest and curing

Curing maincrop for storage: spread lifted tubers in a single layer somewhere dark, dry, and airy for 1-2 weeks so the skins set ("cure"). Then store only undamaged tubers in paper or hessian sacks somewhere cool (40-50°F / 4-10°C), dark, and frost-free. Cured, properly stored maincrop keeps for months.

Safety: green potatoes, sprouts, and pets

Never eat potatoes that are green, sprouting, or bitter. Light and damage trigger the toxic glycoalkaloid solanine. The FDA treats roughly 20-25 mg per 100 g (200-250 ppm) of total glycoalkaloids as the maximum acceptable level, and the highest concentrations sit in the green skin, eyes, and sprouts. Solanine is heat-stable — boiling, frying, or baking does not destroy it. Light surface greening can be deeply peeled away, but discard any tuber that is deeply green or bitter-tasting. Store potatoes cool and dark to prevent greening.

Pets: the ASPCA confirms potato foliage, stems, sprouts, and green/raw tubers are toxic to dogs and cats (and horses) due to solanine and related glycoalkaloids. Cats are especially sensitive. Signs include drooling, vomiting, diarrhea, depression, weakness, and tremors. Cooked plain potato flesh is not the hazard — the plant, sprouts, and green tubers are. Keep the haulm and any culled green tubers off the compost pile pets can reach, and call ASPCA Poison Control at (888) 426-4435 if ingestion is suspected.

Related articles

• When to plant garlic — the other staple that overwinters in the same bed
• How to grow tomatoes — keep them apart from potatoes (shared blight)
• Container vegetable gardening — grow-bag potato sizing
• Companion planting — what to rotate before and after potatoes
• Soil pH guide — keep the potato bed slightly acidic to avoid scab
• Frost date calculator — pinpoint your safe planting window
• How to start a vegetable garden — beginner overview with potatoes in the rotation

Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.