When to Plant Lettuce in Clackamas County, OR
Your May gardening checklist
We've pulled the most time-sensitive tasks for Clackamas County, Oregon this May and put them front and centre. Tackle them in order.
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Get lettuce seeds going inside
You're about 25 weeks out from your last frost — the perfect window to get these germinating indoors.
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Pick lettuce
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Before June arrives, get these ready
- First harvests: lettuce
Lettuce is a fast-growing cool-season green available in leaf, romaine, butterhead, and crisphead types. It is the foundation of salads and one of the easiest crops to grow.
Clackamas County, Oregon is in USDA Zone 9a. The average last spring frost is April 14 and the first fall frost is October 28, giving you a growing season of approximately 197 days.
At an elevation of 199 feet, Clackamas County receives approximately 53.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Lettuce during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Lettuce root diseases.
Clackamas County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.3
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 Clackamas County
How your county's soil matches Lettuce's growing requirements.
Soil pH
Your soil pH (5.7–6.3) overlaps with Lettuce's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Clackamas County is excellent for Lettuce — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.7%) — Lettuce will thrive.
How to Plant Lettuce
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Lettuce
Sow every 3.4 weeks. Last sowing by Aug 29 to harvest before frost.
For a dedicated fall crop, sow by Sep 02.
Plant Water Budget
Monthly Watering Guide for Lettuce
Lettuce needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Lettuce Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 8.3" | 0" | ❄️ Dormant |
| Feb | — | 5.3" | 0" | ❄️ Dormant |
| Mar | — | 4.8" | 0" | ❄️ Dormant |
| Apr | 3" | 4" | 0" | ✅ Rainfall sufficient |
| May | 3" | 3.3" | 0" | ✅ Rainfall sufficient |
| Jun | 3" | 2.1" | 0.9" | 💧 Light watering |
| Jul | 3" | 0.8" | 2.2" | 🚿 Regular watering |
| Aug | 3" | 1" | 2" | 🚿 Regular watering |
| Sep | 3" | 2.2" | 0.8" | 💧 Light watering |
| Oct | 3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 8.2" | 0" | ❄️ Dormant |
| Dec | — | 8.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Clackamas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Lettuce 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.
Lettuce Planting Timeline — Clackamas County, OR
Lettuce Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Direct Sow | March 24 | Mar 24 – Apr 14 |
| Harvest | May 19 | May 19 – Jul 28 |
| Fall Sowing | September 2 | Sep 2 – Sep 16 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Natural rainfall sufficient
📅 Days to Maturity
30–60 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 9a
📆 Growing Season
197 days in Clackamas County
Growing Tips for Lettuce in Clackamas County
Direct sow Lettuce outdoors after April 14 in Clackamas County when soil has warmed and frost danger has passed.
Your generous 197.0-day season in Clackamas County allows multiple plantings of Lettuce. Sow every 15.0 days for continuous harvest.
Common pests for Lettuce in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Sow seeds directly every 2 weeks for continuous harvest. Provide afternoon shade in warm weather to delay bolting. Harvest in the morning for crispest leaves.
Recommended Lettuce Varieties for Clackamas County
Bolt-resistant varieties for warm summers — grow as spring/fall crop
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Very easy to save. Let a few plants bolt each season.
Lettuce in Other Locations
Frequently Asked Questions
When should I plant Lettuce in Clackamas County, OR?
Clackamas County is in Zone 9a with an average last frost of April 14. Plan your Lettuce planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clackamas County, OR?
Clackamas County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 14 and first fall frost is October 28.
Your Clackamas County Garden Planner — Free
A 24-page printable planner built for Clackamas 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.