When to Plant Sweet Potatoes in Lincoln County, WA
Your May game plan for Lincoln County, Washington
A quick May briefing for Lincoln County, Washington gardeners — what's urgent, what's next, and what can wait.
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Direct-sow sweet potatoes
Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.
A few tasks this May that'll pay off in June
- Transplants going out: sweet potatoes
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.
Lincoln County, Washington is in USDA Zone 6b. The average last spring frost is May 19 and the first fall frost is September 26, giving you a growing season of approximately 130 days.
At an elevation of 2,955 feet, Lincoln County receives approximately 21.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Sweet Potatoes during the growing season.
Lincoln County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.6
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 Lincoln County
How your county's soil matches Sweet Potatoes's growing requirements.
Soil pH
Your soil pH (5.5–6.6) overlaps with Sweet Potatoes's range (5.5–6.5), though not a perfect match.
Soil Texture
The silt loam soil in Lincoln 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 (4.3%) — 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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | — | 2.8" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 4.3" | 1.1" | 3.2" | 🚿 Regular watering |
| Jun | 4.3" | 1" | 3.3" | 🚿 Regular watering |
| Jul | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Aug | 4.3" | 0.5" | 3.8" | 🚿 Regular watering |
| Sep | 4.3" | 0.8" | 3.5" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 3.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Lincoln 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 — Lincoln County, WA
Sweet Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 24 | Mar 24 – Apr 7 |
| Transplant Outdoors | June 2 | Jun 2 – Jun 16 |
| Direct Sow | May 26 | May 26 – Jun 16 |
| Harvest | September 1 | Sep 1 – Oct 20 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | — |
| 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
130 days in Lincoln County
Growing Tips for Sweet Potatoes in Lincoln County
Direct sow Sweet Potatoes outdoors after May 19 in Lincoln County when soil has warmed and frost danger has passed.
Your 130.0-day growing season in Lincoln County is tight for Sweet Potatoes (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.
Lincoln County receives only 22" 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 Lincoln County, WA?
Lincoln County is in Zone 6b with an average last frost of May 19. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lincoln County, WA?
Lincoln County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 19 and first fall frost is September 26.
Your Lincoln County Garden Planner — Free
A 24-page printable planner built for Lincoln 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.