When to Plant Yam in Lincoln County, OR
May to-do list for Lincoln County, Oregon
Your Lincoln County, Oregon garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Start yam under lights
These need a head start before your last frost (April 19). Sow into cells now so you're ready to transplant in a few weeks.
True yams are tropical tubers distinct from sweet potatoes, producing large starchy roots that can weigh several pounds. They are a staple food in tropical regions worldwide.
Lincoln County, Oregon is in USDA Zone 9a. The average last spring frost is April 19 and the first fall frost is October 31, giving you a growing season of approximately 195 days.
At an elevation of 267 feet, Lincoln County receives approximately 41.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Yam to ensure they mature before fall.
Lincoln County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.4
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 Lincoln County
How your county's soil matches Yam's growing requirements.
Soil pH
Your soil pH (5.5–6.4) is within Yam's preferred range (5.5–6.5).
Soil Texture
The silt loam soil in Lincoln County is excellent for Yam — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.9%) — Yam will thrive.
How to Plant Yam
Plant Water Budget
Monthly Watering Guide for Yam
Yam needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Yam Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.1" | 0" | ❄️ Dormant |
| Feb | — | 5" | 0" | ❄️ Dormant |
| Mar | — | 4.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| May | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Jun | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Jul | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Aug | 4.3" | 0.7" | 3.6" | 🚿 Regular watering |
| Sep | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Oct | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Nov | — | 6.3" | 0" | ❄️ Dormant |
| Dec | — | 5.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Lincoln County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Yam 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.
Yam Planting Timeline — Lincoln County, OR
Yam Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 8 | Mar 8 – Mar 22 |
| Transplant Outdoors | April 26 | Apr 26 – May 10 |
| Direct Sow | April 19 | Apr 19 – May 10 |
| Harvest | October 25 | Oct 25 – Feb 21 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Harvest |
| February | Harvest |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | — |
| August | — |
| September | — |
| October | Harvest |
| November | Harvest |
| December | Harvest |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
180–330 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: ideal
🗺️ USDA Zone
Zone 9a
📆 Growing Season
195 days in Lincoln County
Growing Tips for Yam in Lincoln County
Direct sow Yam outdoors after April 19 in Lincoln County when soil has warmed and frost danger has passed.
Your 195.0-day growing season in Lincoln County is tight for Yam (180.0-330.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Plant tuber pieces in mounds of loose, rich soil. Provide sturdy trellising for climbing vines. Yams require a long, warm growing season of 8-11 months. Harvest when vines die back.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Yam in Other Locations
Frequently Asked Questions
When should I plant Yam in Lincoln County, OR?
Lincoln County is in Zone 9a with an average last frost of April 19. Plan your Yam planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lincoln County, OR?
Lincoln County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 19 and first fall frost is October 31.
Your Lincoln County Garden Planner — Free
A 24-page printable planner built for Lincoln County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.