How to Grow Sweet Potatoes: Complete Step-by-Step Guide

Plant sweet potato slips after your last frost when soil reaches 65°F (18°C), in loose, well-drained soil with pH 5.8-6.2. Space plants 12-18 inches apart in rows 3-4 feet apart. Water consistently but avoid saturation, and harvest when leaves begin yellowing, typically 90-170 days after planting. Proper curing at 85-95°F with 85-90% humidity for 10-14 days dramatically improves flavor and storage life.

Discover exactly how to grow sweet potatoes successfully in your garden with this comprehensive guide. Whether you're a first-time gardener or looking to improve your harvest, you'll learn proven techniques for planting, caring for, and harvesting sweet potatoes that yield delicious, nutritious tubers. Follow these science-backed methods used by experienced growers to maximize your sweet potato production regardless of your climate zone.

Planning Your Sweet Potato Garden

Selecting the right variety and timing your planting correctly makes all the difference in your sweet potato success. Unlike regular potatoes, sweet potatoes grow from "slips" (rooted sprouts) rather than seed potatoes, and they require a long, warm growing season.

Variety	Days to Maturity	Color/Flavor Profile	Best Growing Zones
Covington	90-100	Deep orange, moist, sweet	6-11
Beauregard	95-105	Bright orange, very sweet	5-11
O'Henry	100-110	Cream flesh, drier texture	6-11
Japanese Purple	110-120	Purple skin, white flesh	7-11

According to the USDA Agricultural Research Service, sweet potatoes require 90-170 frost-free days depending on variety. Northern gardeners should choose earlier-maturing varieties like Covington and start slips indoors 6-8 weeks before planting. Southern gardeners can grow longer-season varieties but must watch for excessive moisture that can cause rot.

Soil Preparation Essentials

Sweet potatoes thrive in loose, well-drained soil that allows tubers to expand without obstruction. Heavy clay soils produce misshapen roots, while sandy soils may require additional organic matter to retain moisture.

Prepare your planting area 2-3 weeks before transplanting:

• Test soil pH and amend to reach 5.8-6.2 (sweet potatoes struggle in alkaline conditions)
• Create raised beds 8-10 inches high to improve drainage and soil warming
• Mix in 2-3 inches of compost but avoid fresh manure which causes excessive vine growth
• Apply balanced organic fertilizer (5-10-10) at planting time

The University of Minnesota Extension recommends avoiding high-nitrogen fertilizers which promote vine growth at the expense of tuber development. Instead, focus on phosphorus and potassium which support root formation.

Planting Your Sweet Potato Slips

Timing your planting correctly ensures your sweet potatoes have enough warm days to mature. Planting too early in cold soil causes stunted growth, while planting too late may not allow enough time for tubers to develop.

Sweet Potato Growing Timeline:

• 8-10 weeks before last frost: Start slips indoors
• After last frost, soil 65°F+: Transplant hardened slips
• 3-4 weeks after planting: First vine growth appears
• 6-8 weeks after planting: Flowers may appear (doesn't affect yield)
• 90-170 days after planting: Harvest when leaves begin yellowing
• Immediately after harvest: Begin curing process

To plant slips properly:

1. Water slips thoroughly before transplanting
2. Dig holes deep enough to cover the entire stem up to the first set of leaves
3. Space plants 12-18 inches apart in rows 3-4 feet apart
4. Water immediately after planting with a root-stimulating solution
5. Avoid mulching initially to allow soil to warm, then apply straw mulch after 2 weeks

For container growing, choose bush varieties like Porto Rico and use containers at least 15 gallons with excellent drainage. The Oregon State University Extension confirms that container-grown sweet potatoes require more frequent watering but can produce excellent yields with proper care.

Care and Maintenance Through the Growing Season

Proper care throughout the growing season ensures healthy plants and maximum tuber development. Unlike many vegetables, sweet potatoes require specific care practices that differ from regular potatoes.

Watering requirements: Provide 1 inch of water weekly, increasing to 1.5 inches during tuber formation (6-8 weeks after planting). Reduce watering 2-3 weeks before harvest to prevent splitting. Overwatering causes cracked tubers and increases disease risk.

Weed management: Hand-pull weeds carefully during the first 4-6 weeks, as sweet potatoes have shallow roots. After vines cover the ground, they naturally suppress weeds. Avoid deep cultivation which damages developing tubers.

Pest and disease prevention: Common issues include sweet potato weevils, root-knot nematodes, and fungal diseases. Rotate crops every 3-4 years and inspect plants weekly. The University of Illinois Extension recommends using floating row covers during early growth to prevent insect damage.

Harvesting and Curing for Maximum Flavor

Knowing when and how to harvest sweet potatoes significantly impacts their flavor, texture, and storage life. Harvesting too early produces small, less sweet tubers, while harvesting too late risks cold damage.

Harvest when:

• Leaves begin turning yellow (typically 90-170 days after planting)
• Soil temperatures remain above 50°F (10°C)
• At least 2-3 weeks before first expected frost

Use a digging fork to carefully loosen soil 8-10 inches from plants, then lift tubers gently. Handle with care as even small bruises reduce storage life. Never leave harvested sweet potatoes in direct sun for more than 30 minutes.

The curing process transforms starches to sugars and heals minor wounds:

1. Clean excess soil (don't wash)
2. Store at 85-95°F with 85-90% humidity for 5-7 days
3. Move to 55-60°F with 75-80% humidity for another 5-7 days
4. Store long-term at 55-60°F with moderate humidity

According to research from Cornell University's College of Agriculture, properly cured sweet potatoes develop up to 30% more beta-carotene and significantly sweeter flavor compared to uncured tubers.

Troubleshooting Common Growing Problems

Even with proper care, sweet potato growers may encounter challenges. Understanding these issues helps you address problems before they ruin your harvest.

Small or misshapen tubers: Usually caused by compacted soil, inconsistent watering, or planting in soil that's too rich. Amend soil with sand or compost for better texture and maintain consistent moisture.

Excessive vine growth, few tubers: Indicates too much nitrogen in soil. Avoid high-nitrogen fertilizers and consider soil testing before planting next season.

Holes in leaves: Likely from flea beetles or leaf miners. Use floating row covers early in the season and encourage beneficial insects like ladybugs.

Soft, mushy spots on tubers: Indicates rot from overwatering or poor drainage. Improve soil structure and reduce watering frequency.

Remember that sweet potatoes grow best in warm climates (zones 6-11), but northern gardeners can succeed with short-season varieties and season extension techniques. The Cooperative Extension System reports that gardeners in cooler zones can add 2-4 weeks to their growing season by using black plastic mulch to warm the soil.

When is the best time to plant sweet potatoes?

Plant sweet potato slips 3-4 weeks after your last frost date when soil temperature reaches at least 65°F (18°C). In warmer zones (7-11), plant between April and July. Northern gardeners should choose early-maturing varieties and consider using black plastic mulch to warm the soil earlier in the season.

Can I grow sweet potatoes in containers?

Yes, you can grow sweet potatoes in containers using bush varieties like 'Porto Rico' or 'Vardaman'. Choose containers at least 15 gallons with excellent drainage, fill with loose potting mix, and provide consistent watering. Container-grown sweet potatoes typically produce smaller yields but can be very successful with proper care.

Why do my sweet potatoes have cracks or splits?

Cracks and splits usually occur from inconsistent watering, particularly after a dry period followed by heavy rain or irrigation. Maintain even soil moisture throughout the growing season, especially during tuber formation (6-8 weeks after planting). Reduce watering 2-3 weeks before harvest to prevent this issue.

How long should I cure sweet potatoes after harvest?

Sweet potatoes need 10-14 days of proper curing to develop their best flavor and storage qualities. First, cure at 85-95°F with 85-90% humidity for 5-7 days, then move to 55-60°F with 75-80% humidity for another 5-7 days. Proper curing dramatically improves sweetness and extends storage life up to 6 months.

What's the difference between sweet potatoes and yams?

True yams are a different plant species (Dioscorea) primarily grown in Africa and Asia, with rough, scaly skin and low moisture content. What Americans call 'yams' are actually orange-fleshed sweet potatoes. All 'yams' sold in US grocery stores are sweet potatoes. True sweet potatoes have tapered ends, smooth skin, and moist flesh when cooked.