When to Plant Sweet Potatoes in Wallowa County, OR
What to do in May
Here's what deserves your attention in Wallowa County, Oregon this month. Everything below is tailored to Zone 6b and timed around your local frost dates.
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Set out sweet potatoes seedlings
Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.
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Scatter sweet potatoes into prepared beds
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
Sweet potatoes are a warm-season root crop that produces nutritious, sweet tubers in orange, white, and purple varieties. They need a long, hot growing season.
Wallowa County, Oregon is in USDA Zone 6b. The average last spring frost is May 11 and the first fall frost is September 22, giving you a growing season of approximately 134 days.
At an elevation of 1,240 feet, Wallowa County receives approximately 22.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Sweet Potatoes during the growing season.
Wallowa County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.2
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 Wallowa County
How your county's soil matches Sweet Potatoes's growing requirements.
Soil pH
Your soil pH (5.3–6.2) overlaps with Sweet Potatoes's range (5.5–6.5), though not a perfect match.
Soil Texture
The silt loam soil in Wallowa County is excellent for Sweet Potatoes — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Sweet Potatoes.
Organic Matter
Organic matter is excellent (5.4%) — Sweet Potatoes will thrive.
How to Plant Sweet Potatoes
Plant Water Budget
Monthly Watering Guide for Sweet Potatoes
Sweet 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 | Sweet Potatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 2.3" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Jun | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Jul | 4.3" | 0.4" | 3.9" | 🚿 Regular watering |
| Aug | 4.3" | 0.4" | 3.9" | 🚿 Regular watering |
| Sep | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Oct | — | 2.1" | 0" | ❄️ Dormant |
| Nov | — | 3.9" | 0" | ❄️ Dormant |
| Dec | — | 3.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Wallowa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet 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.
Sweet Potatoes Planting Timeline — Wallowa County, OR
Sweet Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 16 | Mar 16 – Mar 30 |
| Transplant Outdoors | May 25 | May 25 – Jun 8 |
| Direct Sow | May 18 | May 18 – Jun 8 |
| Harvest | August 24 | Aug 24 – Oct 12 |
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 | — |
| 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
90–120 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 6b
📆 Growing Season
134 days in Wallowa County
Growing Tips for Sweet Potatoes in Wallowa County
Direct sow Sweet Potatoes outdoors after May 11 in Wallowa County when soil has warmed and frost danger has passed.
Wallowa County receives only 23" of rain annually. Sweet Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant slips (rooted sprouts) after soil is thoroughly warm. Build raised mounds for better root development. Cure harvested roots at 80-85F for 10 days to develop sweetness.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Potatoes in Other Locations
Frequently Asked Questions
When should I plant Sweet Potatoes in Wallowa County, OR?
Wallowa County is in Zone 6b with an average last frost of May 11. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Wallowa County, OR?
Wallowa County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is May 11 and first fall frost is September 22.
Your Wallowa County Garden Planner — Free
A 24-page printable planner built for Wallowa County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.