Idaho Gardening Guide (2026)

High desert and mountain valleys; cold nights, hot days, short season.

Garden countdownToday: Aug 19

USDA 2023 zones + NOAA 1991-2020 frost normals. Estimates — check your local forecast before planting.

USDA hardiness zone
37
Region
Mountain
Typical last spring frost
05/10
Typical first fall frost
10/01
Frost-free season
144 days
Lawn grass type
Cool-season

Quick answer (Idaho): Most of the state gardens in USDA zones 37 with about a 144-day frost-free window. Plan around the typical last frost of 05/10; start warm-season crops indoors ~6 weeks earlier. Source: USDA Plant Hardiness Zone Map (2023) + state cooperative extension typical freeze dates.

Your Idaho planting calendar

Pre-filled for Idaho. Pick a crop to see indoor start, sow/transplant, and harvest dates you can print.

In Idaho (typical zone 37, last frost ≈ May 10, first frost ≈ Oct 1, 144-day season), your Tomato plan:

Start seeds indoors
Mar 29
Sow / transplant outdoors
May 24
First harvest
Aug 2
Spacing / depth
24″ / 0.25

Month-by-month (Idaho, 2026)

MonthAction
Jan
Feb
MarStart indoors
Apr
MaySow · Transplant
Jun
Jul
AugHarvest
Sep
Oct
Nov
Dec

Start indoors 6 weeks before last frost; transplant after soil warms. Zones 313 suitable. Dates are typical; confirm with your county extension and watch the 10-day forecast.

Lawns in Idaho

Best grass types for your climate:

Kentucky BluegrassTall FescuePerennial RyegrassFine Fescue

Open the lawn care scheduler →

Common pests in Idaho

The pests most reported in your region, with organic-first treatments:

CutwormAphidsGrasshopper

Cutworm

Targets
Seedlings of many crops
Signs
Young transplants cut at soil line overnight.
Organic / IPM first
Cardboard collar around stem; diatomaceous earth ring; hand-pick at dusk.
Chemical option (follow label)
Bt or spinosad soil drench at planting.
Prevention
Till in fall; avoid fresh manure; start transplants sturdy.

What grows well in Idaho

Crops suitable for zones 37:

CropTypeSpacingDays to harvest
TomatoWarm-season2470
PepperWarm-season1875
LettuceCool-season845
CarrotCool-season365
Green BeansWarm-season455
SpinachCool-season640
CucumberWarm-season1255
ZucchiniWarm-season3650
KaleCool-season1255
BroccoliCool-season1870

Figures are typical (30-year normals) from USDA and state extension services. Always confirm your local last/first freeze and product labels with your county extension before acting.