Vegetable · Fabaceae
Peanut
Arachis hypogaea
Give it full sun, loose sandy soil, and a long warm season, and this forgiving little plant will ripen a whole crop for you underground.
Full sun
Every 5–10 days
64–95°F · 18–35°C
120–150 days
Overview
The peanut may just be the friendliest oddball you can grow at home, and you do not need a green thumb to enjoy it. It blooms above ground like any other plant, then after the flower is pollinated a stalk called the peg bends down and tucks the young pod into the soil, so the nuts ripen quietly out of sight. Despite the name, it belongs to the bean and pea family, not the nut trees.
It first came from South America and simply wants a long, warm season, which is why it settles in happily in zones 7 through 11 and all across the South. The plant stays comfortably low, between 8 and 20 inches tall, and either gathers into a tidy bunch or trails along the ground depending on the type you choose. Give it heat, sun, and a little patience, and it will get along fine.
Peanuts are gentle with a grower who sets the soil up well, and small mistakes are easy to recover from. They love loose, sandy ground rich in calcium so the pegs can slip in and the pods can fill, and as legumes they make much of their own nitrogen for you. Keep them watered steadily while they flower, and come fall you can dig up a heavy, rewarding crop of nuts.
Care
The short version: give peanuts full sun, loose sandy soil with plenty of calcium, and about an inch of water a week while they flower and set pods. Go easy on the nitrogen, since the plant kindly makes its own, and simply ease off the water as the pods mature.
Light
Peanuts love full sun, ideally 8 or more hours a day, and they will thank you for it. A little partial sun is fine, but too much shade leaves you with weak, leggy plants and only a thin crop of pods.
Water
Give about 1 inch of water a week and keep the soil evenly moist while the plant is flowering and sending pegs into the ground, because that stretch matters most for pod fill. Once the pods are maturing, simply ease off the water so the crop can cure and lift cleanly for you.
Soil
Plant them in loose, sandy, well-drained loam that is high in calcium, which lets the pegs push in and the shells fill out nicely. A gently acidic pH of 5.8 to 6.5 suits them, and working a little gypsum in at bloom keeps the calcium right where the pods need it.
Temperature
Peanuts are heat lovers that feel happiest between 64°F and 95°F (18°C to 35°C). They have no tolerance for frost at either end of the season, so it is that long warm middle that quietly fills the pods.
Humidity
Average humidity between 40% and 70% is all they ask for, so this is rarely something to fuss over. Steady airflow matters more than the number, since long spells of wet foliage are what invite leaf spot.
Feeding
Because peanuts are legumes that make their own nitrogen, you can go low on nitrogen and lean instead on phosphorus, potassium, and calcium. Work a little gypsum in at early bloom and pegging, when the pods are starting to form and the plant needs the calcium most.
Pruning
Here is one job you can skip entirely, since peanuts need no pruning at all. Cultivate shallowly to knock down weeds early on, but once the pegs begin entering the soil, leave the ground undisturbed so the developing pods stay safe.
Repotting
not applicable; grown as a field/garden annual from seed each year
Size & spacing
Plants stay comfortably low, from 8 to 20 inches (20 to 50 cm) tall, and spread out to 12 to 35 inches (30 to 90 cm) as the vines run. Give each plant that much room so the pegs have open, welcoming soil to reach.
When to plant
Peanuts just need a long, frost-free stretch of warmth to ripen their crop underground, so there is no rush. Wait until the last frost has passed and the soil has warmed to about 65°F, usually late spring, then settle in for a full season of growth before you dig the crop in fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: After last frost when soil reaches about 65°F, typically late spring (May)
- Harvest: Yellow flowers appear ~6-8 weeks after planting; harvest pods in fall before frost when inner shells show veining and darkened color
Hardiness
USDA hardiness zones: 7–11
Temperature: down to -18°C
Troubleshooting
Most peanut trouble hides where you cannot see it, down among the pods, or slips up quietly from the lower leaves. Once you know what healthy vines should be doing, you can catch a problem early and turn it around. Match what you find below, then act while the season still has time.
Kernels that turned moldy or off-color after harvest
Off-color kernels, a soft fuzz of mold, or a musty smell are the plant's way of warning you about Aspergillus mold and the aflatoxin it makes, which slips in when the crop went thirsty in the field or was stored while still damp. Please never eat or share nuts that look or smell wrong, and toss them out without a second thought. The kind fix is easy: cure the pods soon after harvest and tuck them away cool and dry, and you will rarely see it.
Fix:
- Discard moldy peanuts; do not eat or feed them
- Dry pods promptly and thoroughly after harvest
- Store cured peanuts cool and dry
Green healthy vines, but the pods stayed empty
Take heart, because empty pods under leafy tops almost always trace back to one fixable thing: soil that ran short on calcium or packed too hard in the pegging zone. The pegs simply need soft ground to slip into and enough calcium to plump the shells, so work in a little gypsum at early bloom and keep the moisture steady while the pods fill. Just remember not to hill heavy soil over the crown, since that stops the pegs before they ever reach the dirt.
Fix:
- Apply gypsum (calcium sulfate) at early bloom/pegging
- Grow in loose sandy soil and avoid hilling heavy soil over the crown
- Maintain even moisture during pegging and pod fill
Dark spots creeping up from the lower leaves
If you spot round brown to black marks, often circled by a soft yellow halo, that is early or late leaf spot, a fungus that starts on the oldest leaves and works upward during warm, muggy weather. Do not panic, but do act, because left alone it can strip the foliage and shrink the harvest. Water in the morning to keep leaves dry, plant where peanuts have not grown recently, and reach for a labeled fungicide, and you can hold it back.
Fix:
- Apply a labeled fungicide on a preventive schedule
- Remove or rotate away from previous peanut residue
- Improve air movement and avoid prolonged leaf wetness
Toxicity
You can breathe easy here, since peanuts are a safe, wholesome food for people and pets alike, with no toxin in the plant or the plain nuts. The real cautions are all about how they are served: keep them plain and unsalted, never feed moldy nuts, and watch for peanut butter that contains xylitol, which is dangerous to dogs.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Rest easy, because a plain peanut carries nothing that will poison a cat. The shells can be a choking hazard, though, and rich or salty ones may unsettle the stomach, so keep any treat plain and very small.
Dogs None
A few plain, unsalted peanuts sit fine with most dogs, so no need to worry there. The one real danger hides in certain peanut butters, where xylitol can bring on vomiting, weakness, and collapse, so it truly pays to read the label first.
Horses Safe
You can relax around horses, since the plant and the plain nuts hold no poison for them. Peanut hay even serves as forage in some regions, though the fatty kernels are kindest fed only in small amounts.
Rabbits Safe
Nothing in the peanut plant will harm a rabbit, but the nuts are simply too fatty and starchy for their gentle systems. Lean on hay and greens for them and leave the peanuts aside.
Livestock Safe
Cattle, goats, and sheep can graze peanut foliage and hay with no trouble at all. The only thing to watch is moldy nuts and vines, since aflatoxin can gather in feed that has spoiled.
Birds Safe
Plain, unsalted peanuts make a welcome feeder treat for wild and pet birds alike, so offer them freely. Just keep them dry, since damp nuts grow the molds that carry aflatoxin.
People Safe
For most of us peanuts are a wholesome, protein-rich food enjoyed the world over. The one thing to mind is a peanut allergy, which can be serious in sensitive people, along with tossing any nuts that smell musty or look moldy.
Salted or heavily seasoned peanuts add excess sodium and fat that are not ideal for pets and can cause stomach upset or pancreatitis with rich/fatty intake. MOLDY peanuts can carry aflatoxin and should never be fed. Critically, some commercial PEANUT BUTTER contains XYLITOL, an additive that is highly toxic to dogs even in small amounts and can cause hypoglycemia and liver failure; always check labels.
Varieties
Peanuts sort neatly into four main market types, and the one you grow shapes the size, flavor, and use of the nuts. These are the friendly names worth getting to know.
Runner
A low, spreading grower with medium kernels that covers most U.S. acreage and heads into the peanut butter jar.
Virginia
The large-kerneled favorite you find sold as gourmet in-shell snacks and cocktail peanuts.
Spanish
A small, round, red-skinned peanut that carries extra oil, which is why it lands in candy and pressed oil.
Valencia
A sweet, friendly type holding three or more kernels to a pod that tastes best boiled or roasted right in the shell.
Companions
Plant near
Corn: Tall companion that does not compete heavily and benefits from the nitrogen peanuts fix.
Squash: Sprawling vines provide ground cover while peanuts enrich soil nitrogen.
Keep apart
Cabbage and other brassicas: Heavy feeders that compete and prefer firmer, less sandy soil management than peanuts.
How to propagate
Peanuts grow from their very own kernels, so a single packet of raw seed peanuts is truly all it takes to get a patch going.
SeedModerate
Plant raw, viable seed (kernels) outdoors after last frost when soil is about 65°F · Germinates in about 7-14 days; full maturity in 120-150 days
The best part is that peanuts sprout from their own raw kernels, so all you need is fresh, untreated seed peanuts rather than roasted ones. Tuck them 1 to 2 inches deep in loose sandy soil once the frost is gone and the ground has warmed, and a light dusting of Rhizobium inoculant helps the plant make more of its own nitrogen. Little seedlings poke up in 7 to 14 days, and though the full crop asks for a patient 120 to 150 days to finish underground, it is well worth the wait.
Myths
Peanuts are tree nuts.
Here is a comforting surprise: peanuts are not really nuts. They are legumes in the family Fabaceae, close cousins to beans and peas, and their pods ripen underground after the flower stalk leans down into the soil. A peanut allergy does not automatically mean a tree nut allergy, and the reverse is just as true.
Peanuts grow on bushes or trees like other nuts.
The peanut has a lovely trick almost no other crop shares. Once the flower pollinates itself, a little stalk called the peg reaches down from the plant and tucks the young pod into the soil, where the nuts quietly swell and ripen out of sight.