Utah planting calendar

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

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

Thyme planting timetable for Utah

Stage	When in Utah	Anchor
Start seeds indoors	late February (February 28)	8 weeks before the last frost (late April (Wasatch Front))
Transplant outside	late April (April 25)	0 days after the last frost (late April (Wasatch Front))
First harvest (estimate)	mid-July (July 19)	~85 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 thyme 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 — thyme stall in cold ground even after the air warms, so don't rush them out.

Start seeds indoors 8–10 weeks before the last spring frost; germination takes 14–21 days at 18–21 °C (65–70 °F). Harden off transplants and set out around the date of last frost — thyme is perennial in USDA zones 5–9 (RHS H5) but resents waterlogged soil far more than cold. In the first growing season allow only light harvesting so the plant can establish; full harvests from the second year onward, cutting stems back to 4–5 cm above woody growth.

Frost-risk note

Don't plant before late April (Wasatch Front) — a hard freeze can still set young plants back. 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+ hours direct.
Soil temperature for germination: 18–21 °C (65–70 °F).
Spacing: 6–8 inches (15–20 cm) between plants.
Days to harvest: ~85 days from planting out.

Frequently asked questions

When is the best time to plant thyme in Utah?

In Utah (mostly USDA zone 6b), sow thyme indoors around late February, transplant outdoors late April (after the last frost, late April), and harvest from mid-July. Thyme are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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 thyme in Utah?

Yes. Utah's dominant zone 6b supports thyme — the key is timing. Thyme are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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.