Blog

When to Plant Amaranth in Okanogan County, WA

Amaranth is an ancient grain crop with edible leaves and seeds, rich in protein and micronutrients. It thrives in warm conditions and is drought-tolerant once established.

Okanogan County, Washington is in USDA Zone 5b. The average last spring frost is May 13 and the first fall frost is September 26, giving you a growing season of approximately 136 days.

At an elevation of 3,788 feet, Okanogan County receives approximately 21.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Amaranth to ensure they mature before fall.

Okanogan County, WA (Zone 5b) Short season
136 days
Last Spring Frost May 13
136 growing days
First Fall Frost September 26

Okanogan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 13 Transplant: May 22 🍅 Harvest: Aug 21 – Oct 9
Recommended (50%) ✗ May not fit
Start indoors: Mar 18 Transplant: May 27 🍅 Harvest: Aug 26 – Oct 14
Safe Start (90%) ✗ May not fit
Start indoors: Apr 11 Transplant: Jun 20 🍅 Harvest: Sep 19 – Nov 7

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
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 777 gal / 100 sq ft
Amaranth needs ~1,286 GDD — county provides 1,666 GDD Good fit

Amaranth Planting Timeline โ€” Okanogan County, WA

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 โ€“ Apr 1
Transplant Outdoors May 27 May 27 โ€“ Jun 10
Direct Sow May 20 May 20 โ€“ Jun 10
Harvest August 26 Aug 26 โ€“ Oct 14

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

136 days

Growing Tips for Okanogan County

Direct sow after last frost when soil is warm. Thin seedlings to 18 inches apart. Harvest leaves when young and tender; harvest seeds when flower heads begin to dry.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Level Up Your Garden

Frequently Asked Questions

When should I plant Amaranth in Okanogan County, WA?

Okanogan County is in Zone 5b with an average last frost of May 13. Plan your Amaranth planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Okanogan County, WA?

Okanogan County, Washington is in USDA Hardiness Zone 5b. The average last spring frost is May 13 and first fall frost is September 26.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

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 Okanogan County, WA. Local conditions may vary. Last updated: April 2026.