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When to Plant Watercress in Benton County, WA

Watercress is a semi-aquatic plant with a peppery, tangy flavor rich in vitamins and minerals. It grows naturally along streams and can be cultivated in containers with standing water.

Benton County, Washington is in USDA Zone 7a. The average last spring frost is April 3 and the first fall frost is October 27, giving you a growing season of approximately 207 days.

At an elevation of 2,633 feet, Benton County receives approximately 22.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Watercress during the growing season.

Benton County, WA (Zone 7a) Long season
207 days
Last Spring Frost April 3
207 growing days
First Fall Frost October 27

Benton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (135 days to spare)
Start indoors: Feb 17 Transplant: Mar 24 🍅 Harvest: May 5 – Jun 9
Recommended (50%) ✓ Fits season (130 days to spare)
Start indoors: Feb 27 Transplant: Apr 3 🍅 Harvest: May 15 – Jun 19
Safe Start (90%) ✓ Fits season (127 days to spare)
Start indoors: Mar 16 Transplant: Apr 20 🍅 Harvest: Jun 1 – Jul 6

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
1.5″/week
Rainfall provides
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,922 gal / 100 sq ft
Watercress needs ~800 GDD — county provides 3,312 GDD Excellent fit

Watercress Planting Timeline โ€” Benton County, WA

Watercress Planting Calendar

Activity When Date Range
Start Indoors February 27 Feb 27 โ€“ Mar 13
Transplant Outdoors April 3 Apr 3 โ€“ Apr 17
Direct Sow March 20 Mar 20 โ€“ Apr 10
Fall Sowing August 18 Aug 18 โ€“ Sep 1
Harvest May 15 May 15 โ€“ Jun 19

Plant 0.5" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

40โ€“60 days

Soil pH

6.5 โ€“ 7.5

USDA Zone

Zone 7a

Growing Season

207 days

Growing Tips for Benton County

Grow in containers with trays of water kept fresh. Provide partial shade and cool conditions. Harvest stems by cutting above water level. Replace water frequently to prevent stagnation.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Watercress in Benton County, WA?

Benton County is in Zone 7a with an average last frost of April 3. Plan your Watercress planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Benton County, WA?

Benton County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is April 3 and first fall frost is October 27.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Benton County gardeners in Zone 7a 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 Benton County, WA. Local conditions may vary. Last updated: April 2026.