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When to Plant Cress in Boise County, ID

Garden cress is one of the fastest-growing edibles, producing peppery sprouts in as little as two weeks. It is excellent for microgreens and garnishes.

Boise County, Idaho is in USDA Zone 5b. The average last spring frost is May 18 and the first fall frost is September 27, giving you a growing season of approximately 132 days.

At an elevation of 8,023 feet, Boise County receives approximately 24.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Cress during the growing season.

Boise County, ID (Zone 5b) Short season
132 days
Last Spring Frost May 18
132 growing days
First Fall Frost September 27

Boise County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (93 days to spare)
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: May 19 – Jun 9
Recommended (50%) ✓ Fits season (97 days to spare)
Start indoors: Apr 13 Transplant: May 18 🍅 Harvest: Jun 1 – Jun 22
Safe Start (90%) ✓ Fits season (96 days to spare)
Start indoors: May 12 Transplant: Jun 16 🍅 Harvest: Jun 30 – Jul 21

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 320 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Cress needs ~254 GDD — county provides 1,914 GDD Excellent fit

Cress Planting Timeline โ€” Boise County, ID

Cress Planting Calendar

Activity When Date Range
Start Indoors April 13 Apr 13 โ€“ Apr 27
Transplant Outdoors May 18 May 18 โ€“ Jun 1
Direct Sow May 4 May 4 โ€“ May 25
Fall Sowing July 19 Jul 19 โ€“ Aug 2
Harvest June 1 Jun 1 โ€“ Jun 22

Plant 0.5" deep ยท 2" apart ยท Rows 6" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Harvest
July Fall Sowing
August Fall Sowing
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

14โ€“21 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

132 days

Growing Tips for Boise County

Sow seeds thickly on moist soil or paper towels. Keep moist and harvest when 2-3 inches tall. Succession sow every few days for continuous supply. Grows well indoors year-round.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Cress in Boise County, ID?

Boise County is in Zone 5b with an average last frost of May 18. Plan your Cress planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Boise County, ID?

Boise County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 18 and first fall frost is September 27.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Boise County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Boise County, ID. Local conditions may vary. Last updated: April 2026.