When to Plant Blueberries in Walla Walla County, WA
This month in Walla Walla County, Washington
We've pulled the most time-sensitive tasks for Walla Walla County, Washington this May and put them front and centre. Tackle them in order.
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Transplant blueberries outside
Frost risk is low now in Walla Walla County, Washington. If you've been covering beds overnight, you can stop.
Blueberries are long-lived shrubs producing sweet, antioxidant-rich berries. They require acidic soil and are attractive ornamental plants with fall color and spring flowers.
Walla Walla County, Washington is in USDA Zone 7a. The average last spring frost is April 20 and the first fall frost is October 15, giving you a growing season of approximately 178 days.
At an elevation of 3,151 feet, Walla Walla County receives approximately 23.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Blueberries during the growing season.
Walla Walla County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.4
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 Walla Walla County
How your county's soil matches Blueberries's growing requirements.
Soil pH
Your soil pH (5.2–6.4) is more alkaline than Blueberries prefers (4.5–5.5). Add sulfur or peat moss to lower pH.
Soil Texture
The silt loam soil in Walla Walla County is excellent for Blueberries — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Blueberries will thrive.
How to Plant Blueberries
How Much Blueberries to Grow
For a family of 4, plant approximately 8 blueberries plants in about 192 sq ft. In Walla Walla County's 178-day season, you'll have plenty of time for a full harvest. Plan your garden layout →
Plant Water Budget
Monthly Watering Guide for Blueberries
Blueberries needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Blueberries Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 2.7" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 5.2" | 1.7" | 3.5" | 🚿 Regular watering |
| May | 5.2" | 1.5" | 3.7" | 🚿 Regular watering |
| Jun | 5.2" | 1" | 4.2" | 🚿 Regular watering |
| Jul | 5.2" | 0.4" | 4.8" | 🚿 Regular watering |
| Aug | 5.2" | 0.5" | 4.7" | 🚿 Regular watering |
| Sep | 5.2" | 0.9" | 4.3" | 🚿 Regular watering |
| Oct | 5.2" | 2.2" | 3" | 🚿 Regular watering |
| Nov | — | 3.7" | 0" | ❄️ Dormant |
| Dec | — | 3.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Walla Walla County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Blueberries 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.
Blueberries Planting Timeline — Walla Walla County, WA
Blueberries Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 11 | May 11 – May 25 |
· 48" apart · Rows 72" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 1-2 times/week
📅 Days to Maturity
730–1095 days
🧪 Soil pH
Needs 4.5–5.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
178 days in Walla Walla County
Growing Tips for Blueberries in Walla Walla County
Direct sow Blueberries outdoors after April 20 in Walla Walla County when soil has warmed and frost danger has passed.
Your 178.0-day growing season in Walla Walla County is tight for Blueberries (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.
Walla Walla County receives only 24" of rain annually. Blueberries needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant at least two varieties for cross-pollination. Acidify soil with sulfur or pine needle mulch to maintain pH 4.5-5.5. Protect ripening berries from birds with netting.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Blueberries in Other Locations
Frequently Asked Questions
When should I plant Blueberries in Walla Walla County, WA?
Walla Walla County is in Zone 7a with an average last frost of April 20. Plan your Blueberries planting based on this frost date — see the calendar above for exact timing.
What planting zone is Walla Walla County, WA?
Walla Walla County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is April 20 and first fall frost is October 15.
Your Walla Walla County Garden Planner — Free
A 24-page printable planner built for Walla Walla County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.