State planting calendar

When to plant in Idaho

Idaho spans USDA hardiness zones 3-7. Average last spring frost: late May. Average first fall frost: mid September. This calendar is anchored to University of Idaho Extension's recommendations, with timing adjusted for the dominant climate zone of the state.

By Thomas Joseph Published 2026-06-10 Updated 2026-06-10

Idaho at a glance

USDA hardiness zones	3-7
Region	Mountain West
Average last spring frost	late May
Average first fall frost	mid September
Primary Extension service	University of Idaho Extension

What grows particularly well in Idaho

These are the crops, ornamentals, and trees University of Idaho Extension highlights as well-suited to Idaho's climate:

potato
onion
wheat
peony
aspen
lupine

Idaho planting calendar

Dates are approximate and based on the dominant USDA zone for the state. For zone-specific timing, use the zone finder by ZIP code and frost date lookup tools.

Spring planting (after last frost: late May)

Cool-season vegetables (start 2-6 weeks before last frost outdoors): lettuce, spinach, peas, radishes, carrots, beets, kale, broccoli transplants, cabbage transplants.

Warm-season vegetables (after last frost, soil 60F+): tomato transplants, pepper transplants, beans (direct sow), cucumbers, squash, melons. See the seed starting timeline tool for indoor start dates.

Annual flowers (after last frost): zinnia, marigold, cosmos, sunflower, nasturtium.

Perennials, shrubs, trees: Plant in spring after soil thaws but before summer heat. Best window in Idaho: 4-6 weeks after last frost.

Summer (June - August)

Maintenance season for most Idaho gardens. Mulch heavily, water deeply (1 inch per week), pinch back mums for fall bloom, hand-pull weeds, harvest summer vegetables. Plant fall vegetable starts indoors by mid-July.

Fall planting (before first frost: mid September)

Cool-season vegetables (6-8 weeks before first frost): lettuce, spinach, radish, kale, broccoli, cabbage transplants. Per Penn State Extension, fall vegetable production can equal or exceed spring production with proper timing.

Spring-flowering bulbs: tulip, daffodil, allium, crocus, hyacinth. Plant 4-6 weeks before ground freezes. In Idaho: typically October-November.

Perennials, shrubs, trees: Fall is the best planting season for woody plants in most of Idaho - cooler temperatures + autumn rains reduce transplant stress. Plant 6+ weeks before first hard freeze.

Garlic: Plant cloves in October-November. Harvest the following July.

Winter (December - February)

Most of Idaho is in dormancy. Tasks: order seeds, plan next year, dormant prune fruit trees (February), order bare-root plants for spring delivery. Avoid foot traffic on frozen lawns.

Common Idaho challenges

Short growing season at altitude; cold winters; alkaline soil in much of state; codling moth on apples; rodent damage in winter. For region-specific guidance, see our Mountain West regional gardening guide.

Where to get Idaho-specific advice

The most reliable source for local growing advice is your county Extension office. University of Idaho Extension has county offices that provide free soil testing, plant disease diagnosis, and growing recommendations specific to your microclimate.

Visit University of Idaho Extension for the office nearest you.