When to Plant Spinach in Multnomah County, OR
Spinach is a nutrient-packed cool-season green that grows quickly in spring and fall. It is rich in iron, vitamins, and antioxidants and excellent raw or cooked.
Multnomah County, Oregon is in USDA Zone 8b. The average last spring frost is April 14 and the first fall frost is October 27, giving you a growing season of approximately 196 days.
At an elevation of 357 feet, Multnomah County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Spinach to ensure they mature before fall.
Multnomah County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.3
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 Multnomah County
How your county's soil matches Spinach's growing requirements.
Soil pH
Your soil pH (5.8–6.3) is more acidic than Spinach prefers (6.5–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Multnomah County is excellent for Spinach — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Spinach.
Organic Matter
Organic matter is excellent (4.5%) — Spinach will thrive.
How to Plant Spinach
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Spinach
Sow every 4 weeks. Last sowing by Sep 07 to harvest before frost.
For a dedicated fall crop, sow by Aug 18.
Plant Water Budget
Monthly Watering Guide for Spinach
Spinach needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Spinach Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 5.8" | 0" | ❄️ Dormant |
| Feb | — | 4.1" | 0" | ❄️ Dormant |
| Mar | — | 3.5" | 0" | ❄️ Dormant |
| Apr | 3" | 2.3" | 0.7" | 💧 Light watering |
| May | 3" | 2.3" | 0.7" | 💧 Light watering |
| Jun | 3" | 1.3" | 1.7" | 🚿 Regular watering |
| Jul | 3" | 0.6" | 2.4" | 🚿 Regular watering |
| Aug | 3" | 0.7" | 2.3" | 🚿 Regular watering |
| Sep | 3" | 1.6" | 1.4" | 💧 Light watering |
| Oct | 3" | 2.9" | 0.1" | 💧 Light watering |
| Nov | — | 6" | 0" | ❄️ Dormant |
| Dec | — | 4.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Multnomah County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Spinach 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.
Spinach Planting Timeline — Multnomah County, OR
Spinach Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 10 | Mar 10 – Mar 24 |
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Direct Sow | March 31 | Mar 31 – Apr 21 |
| Harvest | May 19 | May 19 – Jul 21 |
| Fall Sowing | August 18 | Aug 18 – Sep 1 |
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 | Fall Sowing |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.7"/week · Only during dry spells
📅 Days to Maturity
35–50 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 8b
📆 Growing Season
196 days in Multnomah County
Growing Tips for Spinach in Multnomah County
Direct sow Spinach outdoors after April 14 in Multnomah County when soil has warmed and frost danger has passed.
Your generous 196.0-day season in Multnomah County allows multiple plantings of Spinach. Sow every 17.0 days for continuous harvest.
General growing tips
Direct sow as soon as soil can be worked in spring. Plant in partial shade for summer crops to delay bolting. Succession plant every 2 weeks for continuous harvest.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Wind pollinated — isolate 1/2 mile for purity. Easy to let bolt in heat.
Spinach in Other Locations
Frequently Asked Questions
When should I plant Spinach in Multnomah County, OR?
Multnomah County is in Zone 8b with an average last frost of April 14. Plan your Spinach planting based on this frost date — see the calendar above for exact timing.
What planting zone is Multnomah County, OR?
Multnomah County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 14 and first fall frost is October 27.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Multnomah County gardeners in Zone 8b organize planting dates, track what's growing, and never miss a planting window.
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