Sweet Potato
Ipomoea batatas
Sweet potatoes are increasingly popular for warmer regions, with modern UK-adapted varieties like 'Beauregard' and 'Murasaki' giving reliable crops outdoors in the south or under cover further north. They're grown from rooted cuttings called slips, planted out in early June after all frost risk has passed. Slips need warm soil (above 15°C) — fleece or a polytunnel speeds them up. Train trailing vines along the ground or up netting; pinch out tips to encourage tuber formation. Harvest carefully in October before the first frost, when leaves yellow. Cure tubers in a warm, humid place for 7–10 days after lifting — this develops sweetness and toughens the skin for storage. Properly cured sweet potatoes keep for 4–6 months.
Plan where to grow Sweet Potato using our vegetable garden planner.
When to Plant Sweet Potato
Plant sweet potato in May, June.
Time to Harvest Sweet Potato
Expect to harvest approximately 4 months after planting, usually from September to October.
Companion Plants for Sweet Potato
- Broad Beans
Broad beans are cleared by midsummer and leave nitrogen in the soil, so the two can share ground in sequence.
- Sweet Corn
Sweet potato's trailing stems cover the ground beneath sweetcorn, keeping the soil warm and moist and suppressing weeds.
- Thyme
Thyme likes the same warm, sunny, free-draining spot, and its flowers attract beneficial insects.
- Runner Bean
Climbing beans make use of vertical space while sweet potatoes trail at ground level; site the beans so they do not shade the sweet potatoes.
- French Bean
Dwarf French beans like the same warmth and cast little shade over the trailing sweet potato vines.
Expected Yield
Expect 0.5–1.5kg of tubers per plant under good conditions.
Common Problems with Sweet Potato
Poor tuber formation
Caused by cool soil or excessive nitrogen. Plant into warmed soil (use black plastic mulch to raise temperature) and avoid high-nitrogen feeds. Vines should be lush but not overwhelmingly leafy.
Tubers rotting in storage
Untreated tubers rot quickly. Cure for 7–10 days at 25–30°C and high humidity after lifting — this heals nicks and toughens skin. Store at 12–15°C in a frost-free shed or cupboard.
Slug damage to tubers
Slugs hollow out tubers underground. Use nematode controls in summer and lift at the first sign of slug holes. Growing in raised beds or large containers reduces risk.
Sweet Potato: common questions
When should I plant sweet potato in the UK?
Plant sweet potato from May to June.
How far apart should I plant sweet potato?
Space sweet potato about 40cm apart. It grows to around 30cm tall.
When is sweet potato ready to harvest?
In the UK, sweet potato is usually harvested from September to October. It's ready about 4 months after planting.
Does sweet potato come back every year?
Not in a typical UK garden. Sweet Potato is a perennial in warmer climates but is killed by frost here, so it's grown as an annual and started again each year.
What grows well with sweet potato?
Good companions for sweet potato include Broad Beans, Sweet Corn, Thyme, Runner Bean and French Bean. See the companion plants section above for why each one helps.
Is sweet potato frost hardy?
No. Sweet Potato is tender and is damaged by frost, so keep it under cover until all risk of frost has passed and bring it in, or grow it under glass, when nights turn cold.
Plan your sweet potato in the allotment planner
Drag and drop plants onto your plot and get personalised sowing reminders.
Open PlannerMore Vegetables
Yacon
Smallanthus sonchifolius
Yacon is a striking Andean crop producing huge crisp, sweet tubers that taste like a cross between apple and pear. Plant divisions or potted plants in late May…
Celeriac
Apium graveolens var. rapaceum
Celeriac is an underrated vegetable that deserves a place on every UK allotment. This knobbly, celery-flavoured root produces a large, dense bulb above the…
Swiss Chard
Beta vulgaris subsp. vulgaris
Swiss chard is one of the most ornamental vegetables you can grow, with wide, glossy leaves held on thick stems that come in white, red, yellow, orange, and…
Tomatillo
Physalis ixocarpa
Tomatillos are the tangy green fruits inside papery husks that form the base of Mexican salsa verde. They grow like sprawling tomato plants but are more…