How to grow Sweet Potato

Ipomoea batatas

A tender tropical plant grown for its sweet storage roots. It is started from slips (rooted sprouts) and needs warmth, about 21–26 °C, and four to five months without frost.

Quick facts

Type	Vegetable
Family	Convolvulaceae
Light	Full sun
Soil pH	5.5–6.5
Frost	does not tolerate frost
Soil for sowing	from 18 °C
Germination	10 days
Seedlings ready	30 days
Sowing to harvest	100 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Sow for seedlings about 6 weeks before planting out.

Plant out in open ground about a week after your last spring frost, once the soil is warm.

In an unheated greenhouse everything moves about three weeks earlier.

The first harvest comes about 100 days after the shoots appear.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Growth	every 4 days	21…26 °C	potassium, at the start of the stage; potassium, 14 days into the stage
Fruiting	every 5 days	21…26 °C	potassium, at the start of the stage; potassium, 14 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Growth	every 7 days	—	phosphorus and potassium, at the start of the stage
Fruiting	every 7 days	—	—

At home

Stage	Watering	Temperature	Feeding
Growth	every 5 days	21…26 °C	potassium, at the start of the stage; potassium, 14 days into the stage
Fruiting	every 5 days	21…26 °C	potassium, at the start of the stage; potassium, 14 days into the stage

Growing notes

Light

Needs full sun, at least 6 hours of direct light a day and ideally 8–10.

Soil

Loose, well-drained sandy loam, slightly acidic (pH 5.5–6.5). Heavy, wet soil makes the roots rot, and soil too rich in nitrogen gives many leaves but few roots.

Care

Plant slips once the soil is above 18 °C, about 30 cm apart. Water new slips daily for the first two weeks, then give at least 25 mm a week; stop watering 3–4 weeks before harvest so the roots do not split. Use a low-nitrogen fertiliser; in pots give a high-potassium liquid feed every two weeks. Lift the roots 90–120 days after planting, before the first frost, and cure them in a warm place for a week or two.

Pests and diseases of Sweet Potato

Sources

Figures checked against these sources.