How to Grow Sweet Potato

Growing guide

Overview

Sweet potatoes are sprawling, heat-loving vines grown for their sweet, starchy tubers. They need a long, warm season and well-drained soil, but they’re surprisingly easy once the weather cooperates. Growers love them because a single planting can yield a generous harvest that stores for months.

Soil & planting prep

Sweet potatoes grow best in loose, sandy or loamy soil that drains well; heavy clay can cause misshapen roots. Aim for a soil pH of 5.8 to 6.2. Space plants 12 to 18 inches apart in rows 3 feet apart, and plant slips about 3 to 4 inches deep.

When to plant

Plant sweet potato slips outdoors only after the last frost date, when the soil has warmed to at least 65°F (18°C) and nights stay above 55°F. In most regions, that’s 2 to 4 weeks after your average last frost. In cooler zones (5–6), choose the warmest spot and use black plastic mulch to heat the soil early.

How to plant

1. Choose a sunny spot with loose, well-drained soil and work in compost if needed.
2. Wait until the soil is reliably warm (at least 65°F) and all frost danger has passed.
3. Plant slips 3 to 4 inches deep, spacing them 12 to 18 inches apart in rows 3 feet apart.
4. Water gently after planting to settle the soil around the roots.
5. Keep the bed weed-free until the vines spread and shade the ground.

5 common mistakes to avoid

• Planting slips too early in cold soil: sweet potatoes sulk or rot if soil is below 65°F, so wait until the soil is genuinely warm, not just after the last frost date.
• Overwatering or poor drainage: sweet potatoes need moderate water but soggy soil causes root rot and misshapen tubers, so plant in raised beds or sandy soil if drainage is poor.
• Not giving vines enough space: they sprawl aggressively and can smother nearby plants, so allow at least 3 feet between rows or train them up a sturdy trellis.
• Harvesting too early or too late: tubers need 90 to 120 days to size up, but leaving them in cold, wet soil can cause rot, so dig before soil temperatures drop below 50°F.
• Skipping the curing step: freshly dug tubers are starchy and bland; curing them at 85°F and high humidity for a week converts starches to sugars and heals cuts for long storage.

Harvesting & storage

Sweet potatoes are ready when the leaves start to yellow and the tubers have reached full size, usually 90 to 120 days after planting. Dig carefully with a fork, starting a foot away from the plant to avoid nicking the tubers. Cure them in a warm, humid spot (85°F, 85% humidity) for 7 to 10 days, then store in a cool, dark place at 55 to 60°F for several months.

Companion planting

Good companions include beans, corn, and radishes, which don’t compete heavily for nutrients. Avoid planting near tomatoes or other nightshades, as they can share soil-borne diseases.

Growing in containers

Sweet potatoes grow well in containers if you use a large pot — at least 10 gallons per plant — with loose, well-drained potting mix. Place it in full sun and keep the soil evenly moist but not soggy.

Pro tips

Plant slips (rooted cuttings) after soil warms to 18°C. They sprawl — give them space or train vertically. Cure harvested tubers at 30°C for a week to develop sweetness and improve storage.