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When to Plant Mint in Lewis County, WA

Mint is a vigorous perennial herb with refreshing, aromatic leaves used in teas, cocktails, and cooking. It spreads aggressively by underground runners.

Lewis County, Washington is in USDA Zone 7b. The average last spring frost is April 25 and the first fall frost is October 24, giving you a growing season of approximately 182 days.

At an elevation of 327 feet, Lewis County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Mint during the growing season.

Lewis County, WA (Zone 7b) Moderate season
182 days
Last Spring Frost April 25
182 growing days
First Fall Frost October 24

Lewis County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (30 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 31
Recommended (50%) ✓ Fits season (42 days to spare)
Transplant: May 2 🍅 Harvest: Jul 4 – Sep 12
Safe Start (90%) ✓ Fits season (10 days to spare)
Transplant: Jul 1 🍅 Harvest: Sep 2 – Nov 11

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
0.9″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,035 gal / 100 sq ft
Mint needs ~1,088 GDD — county provides 2,639 GDD Excellent fit

Mint Planting Timeline โ€” Lewis County, WA

Mint Planting Calendar

Activity When Date Range
Transplant Outdoors May 2 May 2 โ€“ May 16
Harvest July 4 Jul 4 โ€“ Sep 12

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 7b

Growing Season

182 days

Growing Tips for Lewis County

Always grow mint in containers or with underground barriers to control spreading. Harvest regularly to keep plants compact. Cut plants back in late summer for a fresh fall flush.

Companion Planting

Good Companions

Avoid Planting Near

  • Parsley

Level Up Your Garden

Frequently Asked Questions

When should I plant Mint in Lewis County, WA?

Lewis County is in Zone 7b with an average last frost of April 25. Plan your Mint planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Lewis County, WA?

Lewis County, Washington is in USDA Hardiness Zone 7b. The average last spring frost is April 25 and first fall frost is October 24.

๐ŸŒฑ

Plan Your Garden with Confidence

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