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When to Plant Cress in Washington 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.

Washington County, Idaho is in USDA Zone 6a. The average last spring frost is May 9 and the first fall frost is October 1, giving you a growing season of approximately 145 days.

At an elevation of 4,048 feet, Washington County receives approximately 17.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85ยฐF, providing good warmth for Cress during the growing season. With low rainfall, drip irrigation is essential for growing Cress successfully. Mulch heavily to conserve soil moisture.

Washington County, ID (Zone 6a) Short season
145 days
Last Spring Frost May 9
145 growing days
First Fall Frost October 1

Washington County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (111 days to spare)
Start indoors: Mar 27 Transplant: May 1 🍅 Harvest: May 15 – Jun 5
Recommended (50%) ✓ Fits season (110 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: May 23 – Jun 13
Safe Start (90%) ✓ Fits season (101 days to spare)
Start indoors: May 3 Transplant: Jun 7 🍅 Harvest: Jun 21 – Jul 12

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
0.5″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,210 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Cress needs ~241 GDD — county provides 1,993 GDD Excellent fit

Cress Planting Timeline โ€” Washington County, ID

Cress Planting Calendar

Activity When Date Range
Start Indoors April 4 Apr 4 โ€“ Apr 18
Transplant Outdoors May 9 May 9 โ€“ May 23
Direct Sow April 25 Apr 25 โ€“ May 16
Fall Sowing July 23 Jul 23 โ€“ Aug 6
Harvest May 23 May 23 โ€“ Jun 13

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 Direct Sow
May Transplant Outdoors Direct Sow Harvest
June 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 6a

Growing Season

145 days

Growing Tips for Washington 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 Washington County, ID?

Washington County is in Zone 6a with an average last frost of May 9. Plan your Cress planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Washington County, ID?

Washington County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 9 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Washington County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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