Vegetable · Solanaceae
Potato
Solanum tuberosum
Pop a few cut tubers in the ground, hill and water them well, and you'll dig up plenty come fall.
Full sun
Every 3–7 days
50–77°F · 10–25°C
70–120 days
Overview
Potatoes are cool-season plants and part of the nightshade family, so they're cousins to tomatoes and peppers. They got their start up in the Andes, where folks were growing them for food thousands of years before they made it anywhere else. And the part you actually eat? That's the tuber, a swollen underground stem stuffed with starch, not a root at all.
Most of what matters with potatoes happens down in the dirt where you can't see it. You plant cut chunks of seed potato, each with an eye on it, and up come leafy stems while little underground shoots fatten into tubers. The big job is hilling, which just means pulling soil up around the stems so the young tubers stay buried and out of the light. Let one catch some sun and it'll turn green and bitter, so keep them covered.
Give them loose, rich soil that leans acidic and keep the water coming once the tubers set, and even a little patch can feed a kitchen for months. They also keep really well, so one fall harvest can carry you a long way into winter. Not bad for something that mostly grows itself once it's in the ground.
Care
The short version: potatoes want full sun, loose slightly acidic soil packed with organic matter, and steady moisture once the tubers start forming. Feed them at planting, don't overdo the nitrogen, and keep mounding soil up the stems as they grow.
Light
Potatoes really want full sun, ideally 6 or more hours of direct light a day. They'll get by in partial sun, sure, but the tops come out weaker and the tubers smaller, so give them the sunniest, most open spot you've got. Why settle for a smaller crop if you don't have to?
Water
Keep the soil evenly moist, which works out to about 1 to 2 inches of water a week, and stay extra steady once the tubers start swelling. Just don't let it get waterlogged, because soggy soil is what brings on rot and disease. Think steady and even, not feast or famine.
Soil
Plant them in loose, well-drained sandy loam with lots of organic matter worked in. Potatoes like things a little acidic, a pH of 5.0 to 6.0, which also happens to keep scab from taking hold. And that loose texture? It lets the tubers swell without a fight.
Temperature
These are cool-weather plants, happiest between 50°F and 77°F (10°C to 25°C). Once it gets hot, tuber growth kind of stalls out, which is exactly why starting early pays off and gets them going before summer really hits. A warm spell won't ruin them; they'll just pause and carry on.
Humidity
You don't need to fuss over humidity here, since regular outdoor air is fine for them. What actually matters is good airflow, because damp, crowded leaves are exactly the kind of thing late blight loves. A little space between plants makes a real difference.
Feeding
Mix a balanced fertilizer into the bed when you plant, then give a little nitrogen on the side as the plants come up and you're hilling them. Go easy though, because too much nitrogen just grows big leafy tops instead of the tubers you're actually after. A light hand really is better here.
Pruning
There's basically no pruning to worry about, which is kind of nice. Just pull off any sick-looking leaves when you spot them, and keep hilling soil up the stems to bury the tubers and stop them going green in the light. That mounding is pretty much all the hands-on work they need.
Size & spacing
Plants get about 1 to 3 feet (30 to 100 cm) tall and spread 12 to 24 inches (30 to 60 cm) across. Give each one some room and pile the soil up around it, because that buried space is where all your potatoes actually form. No need to be fussy about it.
When to plant
Potatoes like an early start, back when the ground's still cool, so there's no waiting around for summer. Get the seed pieces in 2 to 4 weeks before your last frost, once the soil's warmed to about 45°F to 50°F (7°C to 10°C). After that, you can sneak out a few new potatoes by midsummer and dig the main storage crop in fall, once the tops have died back.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Early spring, about 2-4 weeks before the last expected frost once soil reaches roughly 45-50°F
- Harvest: Harvest new potatoes about 60-70 days after planting; harvest mature storage potatoes about 90-120 days after planting once tops die back
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Just about every potato problem shows up in one of two spots: on the leaves while they're growing, or on the tubers once you dig them. Only a few really matter, though, and if you catch them early they stay small. Find the one that looks like what you've got below, then sort it out while it's still easy.
Dark greasy spots and leaves that flop over in wet weather
What you're looking at is late blight, the same Phytophthora that goes after tomatoes, and it can rip through a patch after a cool, damp stretch. On humid mornings, check the undersides of the leaves for brown-black spots with pale edges and a bit of white fuzz. Don't wait around: pull and destroy the sick plants right away, skip the compost pile, and toss any rotted tubers before they end up in storage.
Fix:
- Remove and destroy infected plants immediately
- Do not compost infected material
- Apply an approved fungicide preventively where blight is present
- Harvest carefully and cull infected tubers before storage
Stripy beetles and red grubs munching through the leaves
This is the Colorado potato beetle, the crop's number one pest, and a big group can chew a plant right down to nothing. Flip the leaves over and look for orange egg clusters, soft red larvae, and the adults with their ten black stripes. Good news is it's pretty easy to handle: pick them off into soapy water, cover the young plants with row cover, and move the patch to fresh ground each year.
Fix:
- Handpick adults, larvae, and egg masses into soapy water
- Use row covers early in the season
- Apply an approved insecticide if infestation is heavy
- Rotate planting location yearly
Green skin on the potatoes, maybe a bit bitter too
A potato goes green wherever light gets to it near the surface, and that green part carries solanine, the stuff that makes it bitter and unsafe. Usually it's just down to skimpy hilling that left the tubers poking out. Easy fix: mound soil over them as the plants grow, throw out any that are heavily greened, and stash the harvest somewhere cool and dark.
Fix:
- Hill soil up over exposed tubers as plants grow
- Discard heavily greened tubers
- Store harvested potatoes in cool, dark conditions
- Cut away minor green areas before cooking
Rough, corky, scabby spots on the potato skins
Those corky patches are common scab, a soil bacterium that acts up when the ground dries out during tuber set or the pH creeps too high. Peel one and take a look: the marks are only skin-deep and the flesh underneath is just fine, so the crop's still good to eat. Keep the soil evenly moist while the tubers form, hold the pH down around 5.0 to 5.5, and skip the fresh manure.
Fix:
- Maintain even soil moisture during tuber formation
- Keep soil pH slightly acidic (around 5.0-5.5)
- Plant scab-resistant cultivars
- Avoid fresh manure and alkaline amendments
Toxicity
Here's the deal: the cooked tuber on your plate is totally safe to eat, but the rest of the plant isn't. The leaves, stems, sprouts, and any green or raw potato carry a natural toxin called solanine that can make people and animals sick. So cut off any green spots, chuck badly greened tubers, and keep the vines and sprouts away from pets, livestock, and kids.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Caution
If a cat chews on the leaves, stems, or a green sprouted tuber, it's taking in solanine, and you'll usually see drooling and vomiting first, then diarrhea and low energy. A big dose can start affecting the heart and nervous system too, so if it swallowed more than a nibble, give the vet a call.
Dogs Caution
Dogs that dig up and gnaw on raw or green tubers, or nibble the foliage, tend to get an upset stomach, loose stools, and a kind of sluggish, off mood. Keep a close eye on them, because bigger amounts of that glycoalkaloid can throw off the heart rhythm.
Horses Caution
Horses shouldn't get anywhere near the vines or any green or sprouted potatoes. Solanine can bring on colic, drooling, and a dull, wobbly way of standing, and a horse grazing on fallen foliage might take in enough to need the vet.
Rabbits Caution
Don't let rabbits at the leaves, stems, or green tubers, because they're so small that even a little solanine causes real trouble. If any goes down, you'll likely see a poor appetite, a bloated belly, and weakness.
Livestock Caution
Cattle, sheep, pigs, and goats can poison themselves on tossed-out vines or piles of green and cull potatoes left lying in the field. The solanine sets off an upset gut, and once enough builds up you'll see staggering and trembling too, so clear those scraps away.
Birds Caution
Keep chickens and other birds away from the foliage, sprouts, and any greened scraps, since all of that holds solanine. A little plain cooked potato is fine for them, but the green, raw bits are a no-go.
People Cooked tuber safe
A cooked, properly stored potato is a totally safe everyday food. The trouble's all in the green skin, the sprouts and eyes, and every bit of the foliage and stems, which carry solanine that turns a potato bitter and can make you sick, so cut out green spots, toss any badly greened tuber, and keep the vines off your plate.
Cooked, properly stored potato tubers are a safe food. The hazard is the foliage and any green, raw, or sprouted tubers, which contain solanine.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
There are hundreds of potato varieties out there, mostly sorted by skin color, how the flesh cooks up, and what they're best for. These four are the ones you'll bump into in most gardens and grocery stores.
Yukon Gold
Yukon Gold is that thin-skinned yellow potato with buttery, do-anything flesh, and it's pretty much become the go-to variety in most kitchens.
Russet Burbank
Russet Burbank is the big, oblong, brown-skinned one that's so starchy it's the obvious pick whenever you're baking or frying.
Red Pontiac
Red Pontiac is a red-skinned, white-fleshed variety that folks love for its steady yields and how well it holds up in storage.
Kennebec
Kennebec is a tough white potato that cranks out big crops and shrugs off more disease than most, which makes it an easy one to grow.
Companions
Potatoes do well beside nitrogen-fixing beans and a few traditional partners, and badly beside their nightshade relatives and sprawling vines that crowd them and trade diseases.
Plant near
Bush beans: Legumes fix nitrogen and are reported to help repel some potato pests.
Corn: Traditional companion that does not compete heavily and shares no major potato diseases.
Cabbage-family crops: Generally compatible bed companions that do not share potato's key diseases.
Horseradish: Often planted near potatoes and is said to improve overall plant vigor and pest resistance.
Keep apart
Tomato: Another solanaceous crop that shares late blight and other diseases, increasing risk to both.
Cucumbers and squash: Sprawling cucurbits crowd potatoes and can increase disease pressure.
How to propagate
There are two ways to get potatoes going, but honestly, for almost every home gardener only one of them makes any sense.
Bulbs & cormsEasy
Early spring, 2-4 weeks before the last frost · Sprouts emerge in about 2-4 weeks after planting
Just about everyone grows potatoes from certified seed-potato pieces, each cut so it's got an eye or two, then left to dry out for a day or two before planting. Pop them in during early spring, 2 to 4 weeks before the last frost, about 4 inches deep, and you'll see sprouts in roughly 2 to 4 weeks. From there, just keep mounding soil up the stems as they grow taller.
SeedDemanding
Indoors in late winter · Several weeks to germinate and grow on before transplanting
Starting from true botanical seed is a whole different ballgame, sown indoors in late winter and grown on for several weeks before it's ready to transplant. Since the plants come out all over the place, home gardeners usually don't bother, and it stays mostly a breeder thing. For your first go, seed potatoes are the way easier route.
Myths
The whole potato plant must be fine to eat, since the tubers are such a common food.
Not quite. Only cooked tubers that were stored right and never turned green are actually safe. The leaves, stems, sprouts, and any green or raw tuber all carry solanine, which really is toxic, so you can't just munch on the whole plant. Stick to the tubers and leave the green stuff alone.
Potatoes have to be started from true seed, just like other veggies.
Nope. Pretty much every home gardener plants certified seed-potato pieces instead, each one cut so it's got an eye or two. True botanical seed hardly ever gets used outside of breeding, since it gives you a mixed bag of unpredictable plants. So don't go hunting for potato seeds; a few seed potatoes are all you need.