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

Plant sweet potatoes by starting with healthy slips (sprouts) from mature tubers, planting them in well-drained, sandy soil with a pH of 5.8-6.2 after the last frost when soil temperatures reach at least 65°F. Space plants 12-18 inches apart in rows 3-4 feet apart, burying slips up to their first leaves. Water thoroughly after planting, then maintain consistent moisture (about 1 inch per week) throughout the growing season. Most varieties mature in 90-120 days, and proper curing after harvest dramatically improves sweetness and storage life.

Understanding Sweet Potato Basics Before You Plant

Sweet potatoes (Ipomoea batatas) aren't related to regular potatoes—they're actually in the morning glory family. This distinction matters because their growing requirements differ significantly. Unlike Irish potatoes that grow from "seed" pieces, sweet potatoes grow from "slips"—sprouts grown from mature tubers. The USDA Agricultural Research Service confirms sweet potatoes thrive in warm climates but can be successfully grown in most regions with proper timing and care.

Your Sweet Potato Planting Timeline

Timing is everything when learning how to plant sweet potatoes. Follow this science-backed timeline for best results:

Timeline Stage	Action Required	Scientific Basis
8-12 weeks before last frost	Start slips indoors	University of California Extension research shows optimal root development occurs with 8-12 weeks of indoor growth
2 weeks after last frost	Transplant outdoors	Soil must reach minimum 65°F (18°C) for proper root formation (USDA Plant Hardiness Guidelines)
90-120 days after planting	Harvest mature tubers	Most varieties require 90-120 frost-free days to reach full size (Cornell Cooperative Extension)
Immediately after harvest	Cure tubers	10-14 days at 85-95°F with 85-90% humidity improves sweetness and storage (North Carolina State University)

Step-by-Step Sweet Potato Planting Guide

Starting Your Sweet Potato Slips

Don't skip this critical first step when learning how to plant sweet potatoes. You can't plant store-bought sweet potatoes directly—they may contain sprout inhibitors. Instead:

1. Select organic sweet potatoes (untreated with sprout inhibitors)
2. Partially submerge in water using toothpicks (like growing an avocado pit)
3. Place in warm, sunny location (75-80°F ideal)
4. Change water every 2-3 days
5. After 4-6 weeks, harvest slips when 6-9 inches tall

The North Carolina Department of Agriculture confirms this water method produces stronger root systems than direct soil sprouting for beginners.

Preparing Your Garden Bed

Sweet potatoes need specific soil conditions to thrive. Before planting:

• Test soil pH (aim for 5.8-6.2)
• Add 3-4 inches of compost to improve drainage
• Create raised mounds 8-10 inches high
• Space mounds 3-4 feet apart for proper vine growth

Contrary to popular belief, sweet potatoes actually grow better in moderately fertile soil—too much nitrogen produces lush vines but small tubers. The University of Florida IFAS Extension recommends avoiding fresh manure which can cause misshapen roots.

Planting Your Sweet Potato Slips

When transplanting your slips outdoors:

1. Wait until soil temperature reaches 65°F at 4-inch depth
2. Dig holes deep enough to bury slips up to first set of leaves
3. Space plants 12-18 inches apart within rows
4. Water thoroughly immediately after planting
5. Apply 2-3 inches of mulch to retain moisture

Pro tip: Plant slips horizontally with roots spread out rather than vertically—this technique from Louisiana State University research produces more uniform tubers.

Avoiding Common Sweet Potato Planting Mistakes

Even experienced gardeners make these errors when planting sweet potatoes:

• Planting too early - Cold soil below 60°F stunts growth permanently
• Overwatering after planting - Excess moisture causes rot (wait 3-5 days before regular watering)
• Using nitrogen-rich fertilizer - Promotes vines over tubers
• Planting in heavy clay soil - Causes misshapen, cracked tubers

The Clemson Cooperative Extension reports improper soil preparation accounts for 68% of sweet potato growing failures among home gardeners.

Sweet Potato Varieties Compared

Choosing the right variety matters for your climate and space. Here's how popular options compare:

Variety	Days to Maturity	Best Climate	Special Features
Covington	90-100	Warm climates	Disease resistant, orange flesh, excellent storage
Beauregard	90	All regions	High yield, moist texture, early harvest
O'Henry	100-110	Cooler climates	Cream flesh, drier texture, good for baking
Georgia Jet	90	Short seasons	Fastest maturing, heat tolerant

Data sourced from the USDA National Sweetpotato Collaborators Group variety trials (2023).

Ongoing Care for Healthy Sweet Potato Plants

After planting, follow these care guidelines:

• Watering: Provide 1 inch per week—consistent moisture is critical during tuber formation (weeks 5-8)
• Weeding: Hand-pull weeds carefully; sweet potatoes have shallow roots
• Pest control: Watch for sweet potato weevils (use row covers as prevention)
• Vine management: Don't cut vines—they feed the tubers (contrary to popular belief)

According to the Virginia Cooperative Extension, reducing water slightly during the final 3 weeks before harvest improves sweetness and storage quality.

Harvesting and Curing Your Sweet Potatoes

Knowing when and how to harvest affects flavor and storage:

1. Harvest before first frost (tubers damaged below 50°F)
2. Use garden fork to carefully loosen soil around plants
3. Cure immediately at 85-95°F with 85-90% humidity for 10-14 days
4. Store cured potatoes at 55-60°F with moderate humidity

Properly cured sweet potatoes develop complex sugars that dramatically improve flavor—this chemical process is verified by research from the Center for Agriculture and Bioscience International.

Troubleshooting Common Sweet Potato Problems

Address these issues promptly:

• Small tubers: Usually from overcrowding or excessive nitrogen—space plants properly and avoid high-nitrogen fertilizers
• Cracked tubers: Caused by irregular watering—maintain consistent moisture levels
• Yellowing leaves: Could indicate iron deficiency in alkaline soils—apply chelated iron
• Root-knot nematodes: Rotate crops and plant resistant varieties like Covington

Can I plant sweet potatoes from store-bought tubers?

Only if they're organic and untreated. Most store-bought sweet potatoes contain sprout inhibitors that prevent slip growth. Organic sweet potatoes from farmers' markets work best for starting slips.

How deep should I plant sweet potato slips?

Plant slips deep enough to cover the roots and lower stem up to the first set of leaves. Typically this means burying 3-4 inches of the slip, leaving the top leaves above ground. Horizontal planting produces more uniform tubers than vertical planting.

Why are my sweet potatoes misshapen?

Misshapen sweet potatoes usually result from rocky or compacted soil, inconsistent watering, or planting in heavy clay. Prepare soil with ample compost to improve drainage and maintain consistent moisture throughout the growing season.

How long after planting can I harvest sweet potatoes?

Most sweet potato varieties require 90-120 frost-free days to reach maturity. Check maturity by gently digging near the plant base to inspect tuber size. Harvest before soil temperatures drop below 50°F for best results.

Do sweet potatoes need full sun or can they grow in partial shade?

Sweet potatoes require full sun (at least 6-8 hours daily) for optimal tuber development. While vines will grow in partial shade, tuber production significantly decreases with less sunlight. For best results, choose the sunniest location in your garden.