How to Grow Sweet Potatoes

Can you grow sweet potatoes in your US garden?

Sweet potatoes grow in USDA Zones 5-10 as a warm-season annual, needing 90-120 frost-free days with soil temperatures consistently above 65°F. In Zones 7-10, they grow without special techniques. In Zones 5-6, planting through black plastic mulch and choosing short-season varieties like Beauregard (90 days) make a full crop possible.

Sweet potatoes (Ipomoea batatas) are not related to regular potatoes. They are a tropical vine producing edible tuberous roots. They thrive in heat. The warmer the soil and the longer the growing season, the more productive they are. In Zones 8-10, they are one of the most productive crops a home gardener can plant per square foot.

Unlike regular potatoes — planted from seed potatoes or eye-cut pieces — sweet potatoes are planted from slips, which are rooted cuttings grown from a mature sweet potato. Slips establish faster and produce more uniform tubers than any other starting method.

For a broader overview of the vegetable garden setup that works alongside sweet potatoes, see how to start a vegetable garden.

Choosing a sweet potato variety

Variety selection determines both harvest timing and flavor profile. In the US market, orange-fleshed varieties dominate, but white and purple-fleshed types are gaining ground at farmers markets and specialty stores.

For Zone 5-6 northern US gardeners: Beauregard or Georgia Jet are the right choices. Their 90-day maturity leaves a buffer for the shorter frost-free season.

For Zone 7-10 gardeners: Any variety works. Covington is the highest-yielding option for southeastern gardens and is the variety grown by North Carolina’s commercial producers who supply 60% of the US sweet potato market.

Starting sweet potato slips

Slips are rooted stem cuttings from a growing sweet potato. You can buy slips from garden centers in spring (usually sold in bundles of 6-12), or start your own.

To start your own slips:

1. Select an organic sweet potato (conventional sweet potatoes are sometimes treated with sprout inhibitors).
2. Insert toothpicks around the middle and suspend in a jar of water with the bottom third submerged. Or set it in moist potting mix with half the potato buried.
3. Place in a warm location with bright indirect light, at 75-80°F.
4. Sprouts emerge in 3-6 weeks. Each sprout is a potential slip.
5. When sprouts are 4-6 inches long, twist or cut them off the sweet potato just above the base.
6. Remove lower leaves, leaving 2-3 leaves at the top.
7. Rooting slips in water: place stem in a jar of water, changing water every 2-3 days. Roots appear in 7-14 days.
8. Plant in the garden when slips have 3-5 inch roots and frost risk has passed.

Buying slips is faster and more reliable for small gardens. Most US garden centers offer Beauregard and Covington slips from April through June.

Soil preparation for sweet potatoes

Sweet potatoes are one of the most forgiving vegetables in terms of soil fertility — they actually prefer slightly less-fertile soil than most vegetables. High-nitrogen soil pushes vine growth at the expense of tuber development. However, soil structure is critical.

Soil requirements:

• Loose and well-drained: The most important factor. Tubers expand in loose soil; they cannot in compacted or rocky ground.
• pH 5.5-6.5: Slightly acidic. Most US garden soils are in range. Sweet potatoes do not need acidic soil below pH 5.5.
• Low to moderate fertility: Too much nitrogen = big vines, small tubers. Avoid fresh manure or high-nitrogen fertilizers at planting.

Soil preparation steps:

1. Till or fork the bed to 12-15 inch depth.
2. Remove rocks, large clods, and debris that would cause tubers to fork or deform.
3. Add compost at 2-3 inches tilled in — this improves drainage without adding excessive nitrogen.
4. If using raised beds: a mix of 60% topsoil, 30% compost, and 10% coarse sand or perlite provides ideal conditions.
5. Let the bed warm for 2-3 weeks before planting if possible.

Check your planting zones guide to calculate your last frost date and count forward the 3-4 weeks to determine your sweet potato planting window.

Planting sweet potato slips

Timing is the single most important factor in sweet potato success. Plant too early (soil below 65°F) and slips will sit, struggle, or rot. Plant on time and the heat-loving vines take off visibly within a week.

Soil temperature guide by zone:

• Zone 5: Soil reaches 65°F around June 1-15
• Zone 6: May 15-June 1
• Zone 7: May 1-15
• Zone 8-9: April 15-May 1

Planting technique:

1. Make planting holes or furrows 4-6 inches deep.
2. Space holes 12-15 inches apart within rows.
3. Space rows 3-4 feet apart — vines spread 4-6 feet in all directions and need the room.
4. Set each slip in the hole with the rooted end down, burying the stem up to the lowest leaf.
5. Firm soil around the slip and water immediately.
6. Water daily for the first 5-7 days until slips are established. They will wilt initially — this is normal.

Black plastic mulch for Zone 5-6 gardens: Install black plastic sheeting over the prepared bed 1-2 weeks before planting. The plastic raises soil temperature 5-10°F, creating Zone 7 conditions in a Zone 5-6 garden. Cut X-shaped slits 12-15 inches apart and plant through the slits. This technique consistently extends the effective growing season by 2-3 weeks in northern US gardens.

Watering sweet potatoes

Sweet potatoes are drought-tolerant once established, but they need consistent moisture during two critical windows:

Week 1-3 after planting: Water daily or every other day while slips are establishing. The vines will wilt each morning before the root system develops — this is normal and does not require extra watering beyond the scheduled amount.

Month 2-3 (tuber development): Keep soil consistently moist (not wet) during the tuber-filling period. Inconsistent watering during this phase causes misshapen, cracked, or multiple small tubers instead of large single ones.

The last 3-4 weeks before harvest: Reduce watering. Too much water late in the season dilutes flavor and makes tubers prone to storage problems. Some experienced growers stop watering entirely for the last 2 weeks.

After vines are established (3-4 weeks after planting), sweet potatoes tolerate 1-2 weeks without rain in most US zones. Their deep root systems access subsoil moisture.

Feeding sweet potatoes

Less nitrogen than you think. Sweet potatoes fed too much nitrogen produce massive vines and small tubers. The standard recommendation from the North Carolina Cooperative Extension — the leading US authority on sweet potato production — is to avoid nitrogen fertilizer entirely after planting on prepared soil with adequate compost.

If the soil is genuinely poor (sandy, low organic matter), apply a single light dose of balanced fertilizer (10-10-10) at planting time. After that, no additional feeding is needed.

Phosphorus and potassium are the nutrients sweet potatoes respond to most. A soil test is the best guide — how to test soil pH also covers basic nutrient testing. If the soil is adequate in NPK, no supplemental fertilizer is needed for a full crop.

Managing sweet potato vines

Sweet potato vines grow 4-8 feet in all directions by harvest time. They need no training or pruning for production, but there are two management decisions:

Leave vines in place vs. redirect them: As vines grow, they may root at leaf nodes where they touch the ground. These rooted nodes pull energy from the main tuber. Some growers flip vines once or twice during the season to prevent secondary rooting. This is optional but may increase main tuber size in short-season gardens.

Do not remove vines: Some gardeners cut sweet potato vines back to tidy the garden. This significantly reduces yield — leaves are the solar panels driving tuber growth.

Vines as ornamentals: Sweet potato vines are sold as ornamental plants in the US (varieties like ‘Blackie’, ‘Margarita’, ‘Tricolor’). Ornamental types produce edible but small tubers; the vines are the main attraction. Do not confuse ornamental varieties with eating varieties.

Harvesting and curing sweet potatoes

Harvest before first fall frost. A frost will not immediately kill vines (the tops die first) but the cold will damage tubers left in the ground. Plan to harvest 1-2 weeks before your average first fall frost date.

Harvest signs:

• Tubers are the expected size based on variety (check against days-to-maturity; Beauregard is 90-100 days)
• Vine tips begin to yellow or slow growth
• A test dig at one hill shows full-sized tubers

Harvesting technique:

1. Cut vines back to 4-6 inches above the ground.
2. Use a digging fork, starting 12 inches away from the crown to avoid piercing tubers.
3. Lift gently — tubers break easily and broken tubers do not store well.
4. Set harvested tubers on dry ground or paper and let them sit in the sun for 30-60 minutes to dry the surface.

Curing: This is the step most US gardeners skip and then wonder why their sweet potatoes taste starchy. Fresh sweet potatoes contain complex starches, not sugars. Curing converts those starches to sugars, producing the sweet flavor, and heals skin abrasions that would become rot in storage.

Curing method:

1. Place freshly dug sweet potatoes in a single layer in cardboard boxes or crates — do not wash them.
2. Store in a warm (85-90°F), humid location for 10-14 days. Possible locations: near a furnace, in a closed greenhouse, in a heated garage, or in a closet with a space heater maintaining temperature.
3. After curing, move to a cool (55-60°F), dry location for long-term storage.

Properly cured and stored sweet potatoes last 6-12 months. Uncured sweet potatoes stored in the refrigerator or at room temperature deteriorate within 2-3 weeks.

Zone-by-zone sweet potato timing

Pest and disease management

Sweet potatoes in the US home garden have relatively few pest problems compared to other vegetables. The main issues:

Sweet potato weevil: A serious pest in Gulf Coast states (Zone 8-9 coastal areas). The adult weevil lays eggs in tubers; larvae bore through them. Rotating sweet potato location each year and using certified disease-free slips prevents most problems.

Wireworms: The larvae of click beetles bore into tubers in some US soils. More common in ground that was previously lawn. A gap of 2-3 years between sweet potato crops in affected soil reduces populations.

Deer: Deer readily browse sweet potato vines, especially in rural and suburban areas with high deer pressure. Fencing or repellent sprays are the main options — see deer resistant flowers for companion plants that deter deer from nearby beds.

Sweet potatoes are otherwise remarkably trouble-free — one reason they’re worth growing in every US garden where the climate allows a 90-day frost-free window.