How to grow sweet potato
Overview
Sweet potato (Ipomoea batatas) is a warm-season root vegetable prized for its sweet, nutritious tubers. A trailing vine of the Convolvulaceae family, it is grown from slips (rooted cuttings) in warm soil. Key requirement: full sun, consistent moisture, and a long hot growing season of 4–5 months for best yields.
Varieties
- Beauregard — Early maturing variety with copper skin and orange flesh, reliable in temperate and subtropical zones.
- Kumara Red — Classic New Zealand variety with deep red skin, sweet flavour, and good storage.
- Covington — Popular Australian variety with rose skin and orange flesh, high yield and disease resistance.
- Wagga Gold — Australian bred with golden skin and creamy flesh, suited to cooler regions and dry areas.
Soil Preparation
Sweet potato prefers a slightly acidic soil pH of 5.5–6.5. Loosen soil deeply (30 cm) and incorporate well-rotted compost or aged manure. Good drainage is essential to prevent tuber rot; raised beds or ridges are beneficial, especially in heavy soils.
Growing Guide
Plant sweet potato slips into well-drained, sandy loam soil in a full sun position after all frost danger has passed. Space slips 30–45 cm apart in rows 90–100 cm apart, allowing vines to spread. Mound soil into ridges 20–30 cm high to improve drainage and warming. Avoid overwatering until established; then provide consistent moisture, especially during tuber initiation. Harvest when foliage yellows or after 4–5 months.
Care
Apply a low-nitrogen fertiliser high in potassium and phosphorus (e.g., organic potato fertiliser) once vines start running. Avoid over-fertilising with nitrogen to prevent lush foliage at the expense of tubers. Periodically mound soil around the root zone to protect developing tubers from sunburn and pests; water during dry spells.
Companion Planting
Good companions include legumes (which fix nitrogen) and aromatic herbs like dill and borage. Avoid planting with other root crops such as potatoes or carrots to prevent competition and shared pests. Marigolds can help deter nematodes.
Common Pests & Risks
Sweet potato weevil is the most serious pest—look for damage on tubers near the surface. Use crop rotation and remove crop debris. Rodents and wireworms can also damage tubers; keep garden clean and use traps if necessary. In humid areas, fungal leaf spots may occur; ensure good air circulation.
Harvesting
Harvest sweet potatoes before frost or heavy rain in autumn. Dig carefully when leaves start to yellow and die back, typically 4–5 months after planting. Cure harvested tubers in a warm, humid place for 1–2 weeks to improve sweetness and storage life.
In the Kitchen
Sweet potatoes can be baked, roasted, mashed, or fried. Their natural sweetness intensifies with curing. Store in a cool, dark, well-ventilated place for several months; avoid refrigeration.
Troubleshooting
Yellow leaves: overwatering or nitrogen deficiency—reduce watering and check soil. Brown leaf edges: wind damage or salt burn—provide windbreak or flush soil. Small tubers: lack of sunlight or overcrowding—ensure full sun and proper spacing. Cracking tubers: uneven watering—maintain consistent moisture. Holes in tubers: weevil damage—practice crop rotation and use beneficial nematodes.