Vegetable · Convolvulaceae
Sweet Potato
Ipomoea batatas
Give it warm soil, full sun, and a slow summer, and the sweet potato turns a quiet plot into a season-long harvest.
Full sun
Every 5–7 days
64–95°F · 18–35°C
90–120 days
Overview
The sweet potato earns its place in the summer garden as a generous, low-drama crop, a heat-loving vine that spreads across a bed and quietly builds a larder of storage roots beneath it. It belongs to the morning glory family rather than the nightshades that claim the Irish potato, so the shared name is the only thing the two have in common. In a long, warm season a few plants dress an entire plot and pay it back at harvest.
There is an easy rhythm to living with it. The vines roam 3 to 15 feet (90 cm to 4.5 m) and knit into a green groundcover that keeps weeds down and softens the look of a working bed, while the real reward ripens out of sight. It suits a kitchen garden especially well, since the young leaves and shoot tips come indoors as a cooked green, the way spinach does across much of the world.
Its one non-negotiable is warmth, and that shapes the whole gardening year around it. Cold soil leaves it sullen and a frost ends it, so the crop rewards a patient grower who gives it a warm bed and an unhurried summer and lets the roots come into their own on their own schedule.
Care
The short version: set it in full sun on loose, well-drained soil raised into a tidy ridge, keep to about 1 inch of water a week and taper off near harvest, and feed lightly with a low-nitrogen blend so the plant spends itself on roots rather than a sprawl of leaves.
Light
Give it full sun, six to eight hours of it, the light that powers the leafy top and, through it, the crop below. A touch of afternoon shade is no ruin, yet the brighter the position, the more the bed delivers at the end of the season.
Water
Water to roughly 1 inch a week in deep, unhurried soakings, letting the surface dry a little in between. As harvest approaches, ease back, since a sudden drink after a dry spell hurries the roots and leaves them cracked.
Soil
Plant into loose, well-drained loamy or sandy soil, ideally shaped into raised ridges that give the roots room and keep their feet dry. A gently acidic pH of 5.5 to 6.5 suits the crop and asks little tending.
Temperature
This is a warm-country plant at heart, most content between 64°F to 95°F (18°C to 35°C). Cold soil stalls it and frost undoes it outright, so it sets the pace in spring and there is no hurrying it into a cold bed.
Humidity
Everyday summer air in the 40% to 70% range is all it wants, and outdoors the figure hardly enters into the gardening. Warmth and light shape this crop far more than the moisture around it.
Feeding
Restraint serves it best. Work a low-nitrogen fertilizer such as 5-10-10 into the bed before planting, then offer a single sidedress before the vines close over the row. A heavy hand with nitrogen buys lush foliage and shortchanges the roots the season is really for.
Pruning
The roots ask for no pruning at all. Trim the vines only to keep a bed looking cared for or to check their wandering, and let the tender shoot tips earn their keep as cooked greens rather than clippings for the heap.
Size & spacing
The plant keeps a low profile at 6 to 12 inches (15 to 30 cm), while its vines range a generous 3 to 15 feet (90 cm to 4.5 m) across a bed. Grant each one room to spread, or guide the runners back so they sit gracefully beside their neighbors.
When to plant
The sweet potato keeps a warm-season calendar and refuses the frost entirely, which gives the gardening year a clear shape. Start slips indoors from a stored root in late winter, move them out only once spring has warmed the bed, and gather the roots in fall before the first frost draws the season to a close.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Sprout slips from a stored root indoors 6-8 weeks before transplanting
- Plant: After all danger of frost once soil is warm, roughly April through early July
- Harvest: Harvest storage roots in fall before the first frost
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Most of what troubles a sweet potato stays politely out of view until harvest, when it turns up on the roots themselves. The cast is small, a handful of pests and a single fungus, and knowing them is what lets a plot yield clean roots year after year. Find the match below, then set things right before the next season opens.
Stem-end pinholes and dark, bitter tunneling
The culprit is the sweetpotato weevil, the single worst pest the crop contends with. Adults leave small holes near the stem end while the larvae work through the flesh, and their frass-lined tunnels leave the root dark and bitter. Lift and dispose of every affected root and vine, and keep none of that stock back for next year's slips.
Fix:
- Remove and destroy infested roots and vines
- Do not save infested material for propagation
Ragged holes worked into the roots
Wireworms, the lean larvae of click beetles, sink shallow pits that widen into ragged holes as the roots fill out. They gather in ground lately under grass, so a bed that follows sod invites them. Gathering the roots as soon as they size up shortens the window they have to feed.
Fix:
- Harvest promptly once mature to limit feeding time
- Avoid planting in recently turned sod
Dark blotches drifting across the root skin
Scurf is a fungus with a bark worse than its bite, staining the skin and going no further. The blotches widen and merge, yet the flesh beneath stays sound and perfectly good at the table. It travels in on infected planting stock, so retire the worst roots and begin the next crop from clean, disease-free slips.
Fix:
- Discard heavily affected roots
- Start next crop only from clean, disease-free slips
Toxicity
This is a crop you can keep without a second thought, safe for the whole household and its animals. The ASPCA lists the vine as non-toxic to cats, dogs, and horses, and the cooked root and tender greens belong on the table alongside the family. Nothing here asks to be fenced off or shelved out of reach.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Easy company for a cat. A nibbled vine will do no harm, though a large mouthful of any greenery may bring on a little drool or a passing upset stomach.
Dogs None
There is nothing toxic here, and cooked sweet potato already features in many a bowl of dog food. Keep helpings modest, since a fill of fibrous root or vine can loosen the stool.
Horses None
A horse may graze the foliage with no fear of poisoning. As with any rich new feed, bring it in slowly so the digestion has time to settle.
Rabbits Safe
The leaves and vine tips make safe forage, and a little cooked root sits fine alongside. Keep it measured, as too much starchy root at once can unsettle a rabbit's delicate gut.
Livestock Safe
Cattle, goats, and sheep browse the vines and roots safely, and in many places the foliage is raised as fodder in its own right. Clean water and an unhurried change of feed keep everything settled.
Birds Safe
Chickens and other poultry peck happily at cooked root and chopped greens with nothing to fear. Serve it as one part of a varied diet rather than the whole plate.
People Safe
For people, cooked sweet potato is a nourishing staple, and the young leaves and shoots come to the table as a cooked green. Enjoy it freely, mindful only that the raw root is hard to digest in quantity.
Although non-toxic, eating large amounts of any plant material can cause mild stomach upset in pets.
Varieties
Hundreds of cultivars exist, but a short list of orange-fleshed names does most of the work in home gardens. These are the ones worth setting your season by.
Beauregard
A widely planted orange-fleshed favorite, valued for its heavy yields and for coming in earlier than most.
Covington
An NC State introduction, rose-skinned and orange-fleshed, that gives an even, dependably sweet root.
Georgia Jet
A quick orange-fleshed variety that earns its keep in shorter, cooler seasons where others simply run out of time.
How to propagate
The sweet potato skips seed altogether in the garden and arrives instead through slips, the sprouts a single stored root offers up. It is a thrifty, satisfying start, turning a few pantry tubers into a whole bed of plants.
Stem cuttingsEasy
Spring, after the soil has warmed and frost danger has passed · 2 to 3 weeks
The sweet potato begins as slips, the rooted sprouts drawn from a stored root that has started to shoot. Settle them out as cuttings once spring has warmed the bed and frost has passed, and they take hold and root with ease inside 2 to 3 weeks.
Myths
The whole sweet potato plant must be poisonous, given its kinship with the toxic morning glories.
In kitchens around the world the roots and cooked leaves of the food sweet potato are everyday fare, and the ASPCA lists the plant as non-toxic. The confusion belongs to the seeds of certain ornamental morning glories, which are other Ipomoea species and a different concern altogether.
The sweet potato and the ordinary Irish potato are one and the same plant.
They are barely acquainted. The sweet potato is a trailing member of the morning glory family that swells its roots into storage organs, while the Irish potato keeps to the nightshade family and sets its tubers on underground stems.