Utah planting calendar

When to plant sweet potatoes in Utah — sow, transplant & harvest dates

Utah is mostly USDA zone 6b (range 4a-9a). Dates below are derived from sweet potatoes's frost tolerance and Utah's frost window — not generic national averages.

Sweet potatoes planting timetable for Utah

Stage	When in Utah	Anchor
Start seeds indoors	mid-March (March 14)	6 weeks before the last frost (late April (Wasatch Front))
Transplant outside	mid-May (May 16)	21 days after the last frost (late April (Wasatch Front))
First harvest (estimate)	late August (August 29)	~105 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Utah's climate shifts the sweet potatoes dates

Utah's last spring frost averages late April (Wasatch Front) and first fall frost mid-October (Wasatch Front), which sets the whole planting clock. Utah ranges from alpine mountains to warm southern desert. Elevation and aridity drive plant choice; the Wasatch Front has the main growing belt. Wait for warm soil — sweet potatoes stall in cold ground even after the air warms, so don't rush them out.

Sweet potatoes are extremely frost-tender and demand warm soil — do not transplant slips until soil temperature at 4-inch depth holds at 18 °C (65 °F) or above, typically 3 weeks after the last spring frost. Short-season zones (z5-6) should start slips indoors under lights 5-6 weeks early to ensure 100-120 frost-free days. Avoid zones 3-4 without a floating row cover season-extension strategy; in z9-11 slips can go out as early as late March.

Frost-risk note

Don't plant before late April (Wasatch Front) — even a light frost will kill seedlings overnight. In the high Uinta and central mountains (zone 4a) the safe date runs a week or two later.

Regional variation within Utah

the high Uinta and central mountains (zone 4a) runs roughly 1-2 weeks behind the state average; the southwest Dixie around St. George (zone 9a) can plant 1-2 weeks earlier.

Salt Lake City — USDA zone 7a
Provo — USDA zone 7a
St. George — USDA zone 8b
Ogden — USDA zone 7a
Logan — USDA zone 6a

What else to plant in Utah around then

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

Quick-grow guide

Sun: Full sun — 6-8 hours direct.
Soil temperature for germination: Soil 18-24 °C (65-75 °F) for slip rooting.
Spacing: 12-18 inches (30-45 cm) between plants.
Days to harvest: ~105 days from planting out.

Frequently asked questions

When is the best time to plant sweet potatoes in Utah?

In Utah (mostly USDA zone 6b), sow sweet potatoes indoors around mid-March, transplant outdoors mid-May (after the last frost, late April), and harvest from late August. Sweet potatoes are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

What USDA zone is Utah?

Most of Utah sits in USDA hardiness zone 6b, with the state spanning roughly 4a-9a from the high Uinta and central mountains (zone 4a) to the southwest Dixie around St. George (zone 9a). The last spring frost averages late April (Wasatch Front) and the first fall frost mid-October (Wasatch Front).

Can you grow sweet potatoes in Utah?

Yes. Utah's dominant zone 6b supports sweet potatoes — the key is timing. Sweet potatoes are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

Does the planting date change across Utah?

the high Uinta and central mountains (zone 4a) runs roughly 1-2 weeks behind the state average; the southwest Dixie around St. George (zone 9a) can plant 1-2 weeks earlier.

What else can I plant in Utah around the same time?

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.