Sweet Potato Growing Guide
Ipomoea batatas
Skipping the curing step is the single biggest reason homegrown sweet potatoes taste bland — curing converts starches to sugars and can double storage life.
Light
Full sun, 6+ hours daily
Soil
Loose, sandy loam, well-drained, slightly acidic (pH 5.8–6.2)
Water
1 inch per week; reduce 2–3 weeks before harvest
Season
Needs 90–120 warm, frost-free days
Planting
Set out slips after soil warms to 18°C+, well after last frost
Harvest
Before first fall frost, then cure 7–10 days
Sweet potatoes need a long, warm growing season — 90 to 120 frost-free days with consistently warm soil — which makes them a challenge in much of Canada but achievable with black plastic mulch, raised beds, or a greenhouse start. Unlike regular potatoes, they're grown from rooted cuttings called slips rather than seed pieces, and the harvest isn't ready to eat well until it's been cured.
Getting and planting slips
- Sweet potatoes are grown from slips (rooted sprouts), not seed potatoes — buy certified slips from a garden centre or start your own indoors 6–8 weeks before your last frost
- To start your own, suspend a sweet potato half-submerged in water until sprouts form, then root the sprouts individually
- Don't plant slips outdoors until soil has warmed to at least 18°C, usually 2–3 weeks after the last spring frost
- Plant slips 12–18 inches apart in rows 3–4 feet apart, burying the stem up to the first leaves
- Black plastic mulch warms the soil faster and significantly boosts yield in cooler Canadian regions
Working with a short Canadian season
- Choose short-season varieties (Georgia Jet, Beauregard) bred to mature in 90–100 days rather than 120+
- Use raised beds or mounded rows, which warm faster in spring than flat ground
- Black plastic mulch or row covers add crucial extra heat units in cooler regions
- In short-season areas, start slips indoors early rather than buying late so plants have maximum time outdoors
Growing and care
- Water regularly (about 1 inch per week) during the growing season, tapering off 2–3 weeks before harvest to concentrate sugars and prevent splitting
- Vines will sprawl several feet — give them room or train them to stay within the bed
- Avoid high-nitrogen fertilizer, which produces vigorous vines at the expense of root development
- Weed early on; once vines fill in they shade out most weeds on their own
Harvest and curing
- Harvest before the first fall frost — frost damages exposed roots and shortens storage life
- Dig carefully with a fork, starting well away from the base to avoid piercing the roots
- Cure immediately after harvest: hold roots at 27–30°C and high humidity (80–90%) for 7–10 days, then move to cool (13–16°C) storage
- Curing heals cuts and converts starches to sugars — this is what develops the sweet flavour, so don't skip it
- Never wash sweet potatoes before curing or storing; brush off loose soil and wash only right before cooking
Common problems
- Small or bland harvest: usually a season that was too short or too cool — try an earlier variety, black plastic mulch, or starting slips earlier
- Split roots: often caused by irregular watering, especially heavy rain or watering after a dry spell
- Rot in storage: caused by skipping the curing step or storing at too-high humidity after curing
- Vigorous vines but small roots: usually too much nitrogen fertilizer
- Wireworm damage (small holes/tunnels): rotate crops and avoid planting into recently tilled sod
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Frequently asked questions
Yes, in most regions, but the short season is the main challenge — choose an early-maturing variety (90–100 days), use black plastic mulch or raised beds to warm the soil, and start slips indoors well before your last frost.
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