When to Plant Potatoes in Yakima County, WA
Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.
Yakima County, Washington is in USDA Zone 6b. The average last spring frost is May 6 and the first fall frost is October 3, giving you a growing season of approximately 150 days.
At an elevation of 3,150 feet, Yakima County receives approximately 18 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Potatoes during the growing season. With low rainfall, drip irrigation is essential for growing Potatoes successfully. Mulch heavily to conserve soil moisture.
Yakima County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.3
Drainage
Well Drained
Plant 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 Yakima County
How your county's soil matches Potatoes's growing requirements.
Soil pH
Your soil pH (5.5–6.3) is within Potatoes's preferred range (5.0–6.5).
Soil Texture
The silt loam soil in Yakima County is excellent for Potatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Potatoes will thrive.
How to Plant Potatoes
Succession Planting Potatoes
Sow every 8 weeks. Last sowing by Jun 05 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Potatoes
Potatoes needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Potatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.6" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 1.3" | 0" | ❄️ Dormant |
| May | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Jun | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Jul | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Aug | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Sep | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Oct | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 3.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Yakima County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Potatoes 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.
Potatoes Planting Timeline — Yakima County, WA
Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | May 20 | May 20 – Jun 3 |
| Direct Sow | May 13 | May 13 – Jun 3 |
| Harvest | July 29 | Jul 29 – Oct 7 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
70–120 days
🧪 Soil pH
Needs 5–6.5 · Your soil: ideal
🗺️ USDA Zone
Zone 6b
📆 Growing Season
150 days in Yakima County
Growing Tips for Potatoes in Yakima County
Direct sow Potatoes outdoors after May 06 in Yakima County when soil has warmed and frost danger has passed.
Common pests for Potatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
Yakima County receives only 18" of rain annually. Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Potatoes in Other Locations
Frequently Asked Questions
When should I plant Potatoes in Yakima County, WA?
Yakima County is in Zone 6b with an average last frost of May 6. Plan your Potatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Yakima County, WA?
Yakima County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 6 and first fall frost is October 3.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Yakima County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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