Frost Dates for Moscow, ID 83843

Last spring frost May 25 · First fall frost September 20 · 118 frost-free days · USDA Zone 6b

Frost probability for 83843

Frost10%50%90%
Spring (last frost)June 21May 25April 27
Fall (first frost)September 5September 20October 5

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (1.3 km away); the 50% date is the median year.

Frost dates by ZIP code in Moscow, ID

ZIPLast spring frost (50%)First fall frost (50%)Zone
83843May 25September 206b
83844May 25September 206b

Month by month in Moscow

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).
MarchStart peppers and eggplant indoors 8–10 weeks before your last frost (around May 25). Start tomatoes about two weeks later, 6–8 weeks before last frost.
AprilStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
MayLast frost around May 25. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
JuneFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
JulySuccession plant lettuce and greens. Keep beds weeded and watered consistently.
AugustFirst fall frost approaching (around September 20). Transplant fall brassicas. Sow spinach, arugula, and radishes.
SeptemberFirst frost around September 20. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
OctoberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
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 118-day season

Frequently Asked Questions

What is the last frost date for Moscow, ID (ZIP 83843)?

The median last spring frost date for Moscow, ID (ZIP code 83843) is around May 25. 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 Moscow, ID?

The median first fall frost date for Moscow, ID is around September 20. 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 Moscow, ID?

The frost-free growing season in Moscow is about 118 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 Moscow, ID?

Based on frost date patterns, Moscow 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 Moscow, ID?

Start tomato seeds indoors 6–8 weeks before your last frost date (around May 25). For Moscow, that's roughly March 30 to April 13. Transplant outdoors 1–2 weeks after your last frost.

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