Frost Dates for Prineville, OR 97754

Last spring frost July 5 · First fall frost August 23 · 49 frost-free days · USDA Zone 6b

Frost probability for 97754

Frost10%50%90%
Spring (last frost)July 23July 5June 17
Fall (first frost)August 3August 23September 11

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (30.1 km away); the 50% date is the median year.

Month by month in Prineville

MonthWhat to do
JanuaryPlan your garden layout and order seeds. Research varieties suited to your frost dates.
FebruaryStart the slowest-growing crops indoors: onions, leeks, and celery (10–12 weeks before last frost).
MarchOrganize planting supplies and seed-starting mix. Check stored garden tools.
AprilOrganize planting supplies and seed-starting mix. Check stored garden tools.
MayStart peppers and eggplant indoors 8–10 weeks before your last frost (around July 5). Start tomatoes about two weeks later, 6–8 weeks before last frost.
JuneStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
JulyLast frost around July 5. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
AugustFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
SeptemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
OctoberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.
NovemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.
DecemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.

What grows in a 49-day season

Frequently Asked Questions

What is the last frost date for Prineville, OR (ZIP 97754)?

The median last spring frost date for Prineville, OR (ZIP code 97754) is around July 5. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Prineville, OR?

The median first fall frost date for Prineville, OR is around August 23. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Prineville, OR?

The frost-free growing season in Prineville is about 49 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Prineville, OR?

Based on frost date patterns, Prineville falls approximately in 6b. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Prineville, OR?

Start tomato seeds indoors 6–8 weeks before your last frost date (around July 5). For Prineville, that's roughly May 10 to May 24. Transplant outdoors 1–2 weeks after your last frost.

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