UK sowing calendar
When to sow sweet potatoes in the UK
🫙 Best under glass — greenhouse or polytunnel in most of the UK
Sweet potatoes sowing calendar (UK)
| Sow under cover | Apr-May (root/grow on slips indoors) |
|---|---|
| Sow / plant outdoors | late May-Jun (after last frost) |
| Harvest | Sep-Oct (before first frost) |
Tender and heat-loving - grown from slips (cuttings) or plug plants started warm indoors in Apr-May and only planted out once all frost has passed. They crop reliably only under cover (greenhouse, polytunnel or cloches); outdoors they are marginal in the UK and need the warmest, most sheltered spot. Lift Sep-Oct before frost.
UK timing runs on the last-frost date, not a USDA zone. Most of Britain sees its last frost around mid-May, with the north and exposed inland gardens a week or two later and the mild south-west and coast earlier. Tender crops start under cover and only go out once frost has passed; hardy crops can be direct-sown as soon as the soil is workable.
Timing aligned with the RHS grow-your-own guide for sweet potatoes.
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When to sow sweet potatoes in the UK — FAQs
When should I sow sweet potatoes in the UK?
Sow sweet potatoes under cover Apr-May (root/grow on slips indoors), then outdoors late may-jun (after last frost). Tender and heat-loving - grown from slips (cuttings) or plug plants started warm indoors in Apr-May and only planted out once all frost has passed. They crop reliably only under cover (greenhouse, polytunnel or cloches); outdoors they are marginal in the UK and need the warmest, most sheltered spot. Lift Sep-Oct before frost.
Can you sow sweet potatoes outdoors in the UK?
Sweet potatoes is tender and largely greenhouse-only in the UK — outdoors it is marginal and only worth trying in the warmest, most sheltered spots. Tender and heat-loving - grown from slips (cuttings) or plug plants started warm indoors in Apr-May and only planted out once all frost has passed. They crop reliably only under cover (greenhouse, polytunnel or cloches); outdoors they are marginal in the UK and need the warmest, most sheltered spot. Lift Sep-Oct before frost.
When is sweet potatoes ready to harvest in the UK?
Sweet potatoes is typically harvested Sep-Oct (before first frost) in the UK, depending on your sowing date, cultivar and region.
Is it too late to sow sweet potatoes?
It depends on the month and your region. Sweet potatoes has a UK outdoor window of late may-jun (after last frost); northern and exposed gardens run a week or two behind the south. Open Growli and tell it your postcode for timing tuned to your own last-frost date.