Sweet potatoes love heat, and Zone 7 summers deliver it — making this one of the most rewarding warm-season crops for the zone. This guide covers when to plant sweet potatoes zone 7 in detail: the sowing, transplanting and harvest windows for USDA Zone 7, plus spacing, soil, water, companions, pests and storage — all based on USDA zone averages and standard published crop ranges.
Zone 7 covers areas with average annual minimum temperatures of 0 to 10°F. The average last spring frost falls in the Mar 15–Apr 1 range and the average first autumn frost in the Nov 1–15 range. These are USDA zone averages, not exact dates for any one garden — check your local extension service and the forecast before planting tender crops outside. The frost-free season runs roughly seven months, from late March into early November,
When to plant sweet potatoes in Zone 7
Sweet potatoes grow from slips — shoots sprouted from a tuber — not from seed. Start slips indoors in March or April by suspending a tuber in water or burying it in moist compost, then snapping off the shoots once they are several inches tall and rooting them in water. Wait until the soil is genuinely warm before planting out.
The table below puts the whole season on one page. All dates are ranges worked back from the Zone 7 frost averages (Mar 15–Apr 1 last frost, Nov 1–15 first frost) and the crop's published days to maturity (90–120 days). Use the frost date calculator to check the averages for your own area, and confirm them with your local extension service.
| Stage | Zone 7 window | Notes |
|---|---|---|
| Start indoors | Start slips indoors Mar–Apr, 6–8 weeks before transplanting | Germination takes 14–21 days |
| Direct sow outdoors | — (grow from slips, not seed) | Sow into moist, prepared soil |
| Transplant outdoors | Mid-May–early June, when the soil is warm | Harden seedlings off first |
| First harvest | Sep–Oct, 90–120 days after transplanting, before the first frost | 90–120 days to maturity |
| Autumn / second sowing | — (a heat-loving crop; harvest before frost) | Count back from the first frost |
Starting and planting
Transplant slips in mid-May to early June, spacing them 12–18 inches apart in rows 3 feet apart, in loose, well-drained soil with a pH of 5.5–6.5. Sweet potatoes need warmth above all: black plastic mulch warms the soil and suppresses weeds, and the vines will sprawl widely, so give them room or train them up a fence.
Before sowing, fork the bed over, remove weeds and stones, and dig in well-rotted compost. Sweet Potatoes grows best at a soil pH of 5.5–6.5 — test your soil through your local extension service before amending it.
Spacing, sun and soil
Space plants 12–18 inches apart. Crowded plants compete for light, water and nutrients, stay small, and invite disease through poor airflow, so thin seedlings to the final spacing once they are established.
This crop needs full sun — at least six hours of direct sun a day, and more is better. In Zone 7, a south-facing bed or an open spot away from trees and fences gives the strongest growth and the best flavour.
Soil should be deep, fertile and free-draining, with a pH of 5.5–6.5. Heavy clay improves with compost and organic matter, and raised beds help where drainage is poor.
Watering
Water needs are moderate: aim for steady, even moisture rather than feast-and-famine watering. About an inch of water a week from rain or irrigation is a useful guide in most Zone 7 summers, more in hot, dry spells. Water at the base of the plant in the morning, mulch to hold moisture, and avoid wetting the leaves, which invites disease.
Companion planting
Good companions for sweet potatoes include marigolds, basil, onions, lettuce. Planting companions nearby can help with pest confusion, pollination and making the most of bed space — marigolds, for example, are a classic companion across the vegetable garden. The companion planting finder can suggest combinations for your whole bed. Avoid planting sweet potatoes where others of the same family (Convolvulaceae) grew last year: rotate crops each season to reduce soil-borne disease and pest build-up.
Common pests and problems
Watch for aphids, slugs, cutworms. - Aphids — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
- Slugs — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
- Cutworms — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
Beyond pests, the main problems are weather-related: a late frost after transplanting, drought at a critical stage, or waterlogged soil after heavy rain. Cover tender plants with frost cloth if a late frost threatens, and mulch to even out soil moisture.
Harvest and storage
Harvest in September to October, 90–120 days after transplanting, and always before the first frost — frost blackens the vines and damages the roots. Dig carefully with a fork, since sweet potato skins are thin and bruise easily, and handle the roots gently.
Cure sweet potatoes for a week or two in a warm, humid place so their skins toughen and their flavour sweetens, then store in a cool, dark spot. Properly cured roots keep for months — one of the best-storing crops in the Zone 7 garden.
The classic Zone 7 mistake with sweet potatoes is planting slips out too early. Cold soil stalls them for weeks — wait until mid-May or later, when the soil is warm, and they will race away.
Frequently asked questions
When should I plant sweet potatoes in Zone 7?
Sweet potatoes grow from slips — shoots sprouted from a tuber — not from seed. Work from the table above, using the average last frost (Mar 15–Apr 1) and first frost (Nov 1–15), with 90–120 days to maturity. These are USDA zone averages, not exact dates for any one garden — check your local extension service and the forecast before planting tender crops outside.
How much sun does sweet potatoes need in Zone 7?
Full Sun — at least six hours of direct sun a day where possible. Give it the sunniest spot you have.
What soil pH does sweet potatoes prefer?
A pH of 5.5–6.5. Test your soil before amending it, and add compost to improve structure whatever the pH. Your local extension service can test a sample and recommend amendments.
What pests attack sweet potatoes in Zone 7?
The most common are aphids, slugs, cutworms. Inspect plants weekly, hand-pick larger pests, wash small ones off with water, and keep the bed clean and well-spaced so air circulates.
How do I store sweet potatoes after harvest?
Cure sweet potatoes for a week or two in a warm, humid place so their skins toughen and their flavour sweetens, then store in a cool, dark spot. Properly cured roots keep for months — one of the best-storing crops in the Zone 7 garden.
See the Zone 7 May planting guide for what else to sow and plant in the same month, browse the full planting calendar, and try the Harvest Date Calculator to plan your dates. For a related crop, see when to plant butternut squash in Zone 7.