When to Plant Amaranth in Willamina, OR
June to-do list for Yamhill County, Oregon
A quick June briefing for Yamhill County, Oregon gardeners — what's urgent, what's next, and what can wait.
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Time to start amaranth inside
These need a head start before your last frost (April 15). Sow into cells now so you're ready to transplant in a few weeks.
July will be here before you know it — start on
- First harvests: amaranth
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.
Willamina, Oregon is in USDA Zone 8b. The average last spring frost is April 15 and the first fall frost is October 27, giving you a growing season of approximately 195 days.
At an elevation of 476 feet, Yamhill County receives approximately 54.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Amaranth during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Amaranth root diseases.
Willamina Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.2
Drainage
Well Drained
Amaranth Planting Risk Windows
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.
Soil Compatibility in Willamina
How your county's soil matches Amaranth's growing requirements.
Soil pH
Your soil pH (5.4–6.2) is more acidic than Amaranth prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Yamhill County is excellent for Amaranth — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Amaranth.
Organic Matter
Organic matter is excellent (4.3%) — Amaranth will thrive.
How to Plant Amaranth
Amaranth Water Budget
Monthly Watering Guide for Amaranth
Amaranth needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Amaranth Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.4" | 0" | ❄️ Dormant |
| Feb | — | 6.4" | 0" | ❄️ Dormant |
| Mar | — | 5.1" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| May | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Jun | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Jul | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Aug | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Sep | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Oct | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Nov | — | 9.3" | 0" | ❄️ Dormant |
| Dec | — | 8.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Yamhill County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Amaranth Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Amaranth Planting Timeline — Willamina, OR
Amaranth Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | April 29 | Apr 29 – May 13 |
| Direct Sow | April 22 | Apr 22 – May 13 |
| Harvest | July 29 | Jul 29 – Sep 16 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8b
📆 Growing Season
195 days in Yamhill County
Growing Tips for Amaranth in Willamina
Direct sow Amaranth outdoors after April 15 in Yamhill County when soil has warmed and frost danger has passed.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Amaranth in Other Locations
Your Yamhill County Garden Planner — Free
A 22-page printable planner built for Yamhill County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.