Oregon planting calendar

When to plant rosemary in Oregon — sow, transplant & harvest dates

Oregon is mostly USDA zone 8b (range 4b-9b). Dates below are derived from rosemary's frost tolerance and Oregon's frost window — not generic national averages.

Rosemary planting timetable for Oregon

Stage	When in Oregon	Anchor
Start seeds indoors	early February (February 4)	10 weeks before the last frost (mid-April (Willamette Valley))
Transplant outside	late April (April 29)	14 days after the last frost (mid-April (Willamette Valley))
First harvest (estimate)	late July (July 28)	~90 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 Oregon's climate shifts the rosemary dates

Oregon's last spring frost averages mid-April (Willamette Valley) and first fall frost early November (Willamette Valley), which sets the whole planting clock. Oregon is split by the Cascades: a mild, wet, long-season west and a cold, dry, short-season high desert east. Wait for warm soil — rosemary stall in cold ground even after the air warms, so don't rush them out.

Start seeds indoors 10–12 weeks before the last frost; germination is slow and erratic (14–21 days at 18–21 °C / 65–70 °F) with low viability, so propagation by stem cuttings is preferred by most Extension services. Transplant outdoors after the last frost once soil has warmed — rosemary is perennial only in USDA zones 7–10 (established plants survive to about −12 °C / 10 °F); in zones 6 and colder treat as a tender annual or overwinter potted plants indoors before the first autumn frost. Tip harvests of stem ends begin around 80–100 days from transplant.

Frost-risk note

Don't plant before mid-April (Willamette Valley) — a hard freeze can still set young plants back. In the high desert and Cascades east of the mountains (zone 4b) the safe date runs a week or two later.

Regional variation within Oregon

the high desert and Cascades east of the mountains (zone 4b) runs roughly 1-2 weeks behind the state average; the Willamette Valley and southwest interior (zone 9b) can plant 1-2 weeks earlier.

Portland — USDA zone 9a
Eugene — USDA zone 8b
Salem — USDA zone 8b
Bend — USDA zone 6b
Medford — USDA zone 8a

What else to plant in Oregon 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: 18–36 inches (45–90 cm) between plants.
Days to harvest: ~90 days from planting out.

Frequently asked questions

When is the best time to plant rosemary in Oregon?

In Oregon (mostly USDA zone 8b), sow rosemary indoors around early February, transplant outdoors late April (after the last frost, mid-April), and harvest from late July. Rosemary are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is Oregon?

Most of Oregon sits in USDA hardiness zone 8b, with the state spanning roughly 4b-9b from the high desert and Cascades east of the mountains (zone 4b) to the Willamette Valley and southwest interior (zone 9b). The last spring frost averages mid-April (Willamette Valley) and the first fall frost early November (Willamette Valley).

Can you grow rosemary in Oregon?

Yes. Oregon's dominant zone 8b supports rosemary — the key is timing. Rosemary are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across Oregon?

the high desert and Cascades east of the mountains (zone 4b) runs roughly 1-2 weeks behind the state average; the Willamette Valley and southwest interior (zone 9b) can plant 1-2 weeks earlier.

What else can I plant in Oregon 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.