When to Plant Pumpkin in Clackamas County, OR
Your May gardening checklist
Here's what deserves your attention in Clackamas County, Oregon this month. Everything below is tailored to Zone 9a and timed around your local frost dates.
-
Sow pumpkin in trays indoors
Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.
Pumpkins are large-fruited squash varieties grown for eating, decoration, and seed production. They require ample space and a long, warm growing season.
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 Pumpkin during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Pumpkin 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 Pumpkin's growing requirements.
Soil pH
Your soil pH (5.7–6.3) overlaps with Pumpkin's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Clackamas County is excellent for Pumpkin — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.7%) — Pumpkin will thrive.
How to Plant Pumpkin
Plant Water Budget
Monthly Watering Guide for Pumpkin
Pumpkin needs approximately 1.3 inches of water per week (5.6" per month). Here's how your county's rainfall compares month by month.
| Month | Pumpkin Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 8.3" | 0" | ❄️ Dormant |
| Feb | — | 5.3" | 0" | ❄️ Dormant |
| Mar | — | 4.8" | 0" | ❄️ Dormant |
| Apr | 5.6" | 4" | 1.6" | 💧 Light watering |
| May | 5.6" | 3.3" | 2.3" | 💧 Light watering |
| Jun | 5.6" | 2.1" | 3.5" | 🚿 Regular watering |
| Jul | 5.6" | 0.8" | 4.8" | 🚿 Regular watering |
| Aug | 5.6" | 1" | 4.6" | 🚿 Regular watering |
| Sep | 5.6" | 2.2" | 3.4" | 🚿 Regular watering |
| Oct | 5.6" | 4.7" | 0.9" | 💧 Light watering |
| 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.
Pumpkin 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.
Pumpkin Planting Timeline — Clackamas County, OR
Pumpkin Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 21 | Apr 21 – May 5 |
| Direct Sow | April 14 | Apr 14 – May 5 |
| Harvest | July 21 | Jul 21 – Sep 8 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.3"/week · Only during dry spells
📅 Days to Maturity
85–120 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 9a
📆 Growing Season
197 days in Clackamas County
Growing Tips for Pumpkin in Clackamas County
Direct sow Pumpkin outdoors after April 14 in Clackamas County when soil has warmed and frost danger has passed.
Common pests for Pumpkin in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow on mounds after last frost. Allow 6-10 feet between plants. Slip a board under developing fruit to prevent rot. Harvest when rind is hard and deep in color.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Pumpkin in Other Locations
Frequently Asked Questions
When should I plant Pumpkin in Clackamas County, OR?
Clackamas County is in Zone 9a with an average last frost of April 14. Plan your Pumpkin 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.