When to Plant Zucchini in Union County, OR
Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.
Union County, Oregon is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.
At an elevation of 2,751 feet, Union County receives approximately 23.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Zucchini during the growing season.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.6
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 Union County
How your county's soil matches Zucchini's growing requirements.
Soil pH
Your soil pH (5.2–6.6) is more acidic than Zucchini prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Union County is excellent for Zucchini — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Zucchini.
Organic Matter
Organic matter is excellent (5.6%) — Zucchini will thrive.
How to Plant Zucchini
Succession Planting Zucchini
Sow every 5.1 weeks. Last sowing by Jul 28 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Zucchini
Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Zucchini Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 5.2" | 1.5" | 3.7" | 🚿 Regular watering |
| Jun | 5.2" | 0.9" | 4.3" | 🚿 Regular watering |
| Jul | 5.2" | 0.4" | 4.8" | 🚿 Regular watering |
| Aug | 5.2" | 0.5" | 4.7" | 🚿 Regular watering |
| Sep | 5.2" | 1" | 4.2" | 🚿 Regular watering |
| Oct | — | 2" | 0" | ❄️ Dormant |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 4.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Union County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Zucchini 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.
Zucchini Planting Timeline — Union County, OR
Zucchini Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 7 | Apr 7 – Apr 21 |
| Transplant Outdoors | May 26 | May 26 – Jun 9 |
| Direct Sow | May 19 | May 19 – Jun 9 |
| Harvest | July 14 | Jul 14 – Sep 8 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 2-3 times/week
📅 Days to Maturity
45–60 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
137 days in Union County
Growing Tips for Zucchini in Union County
Direct sow Zucchini outdoors after May 12 in Union County when soil has warmed and frost danger has passed.
Common pests for Zucchini in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
Union County receives only 24" of rain annually. Zucchini needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow after last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.
Recommended Zucchini Varieties for Union County
Quick-producing varieties for shorter seasons
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Zucchini in Other Locations
Frequently Asked Questions
When should I plant Zucchini in Union County, OR?
Union County is in Zone 5b with an average last frost of May 12. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, OR?
Union County, Oregon is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is September 26.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Union County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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