When to Plant Fennel in Adams County, WA
Florence fennel is grown for its swollen bulb-like stem base, which has a mild anise flavor. It is crisp raw in salads and sweet when roasted or braised.
Adams County, Washington is in USDA Zone 6b. The average last spring frost is May 7 and the first fall frost is October 3, giving you a growing season of approximately 149 days.
At an elevation of 2,402 feet, Adams County receives approximately 17.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Fennel during the growing season. With low rainfall, drip irrigation is essential for growing Fennel successfully. Mulch heavily to conserve soil moisture.
Adams County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.4
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 Adams County
How your county's soil matches Fennel's growing requirements.
Soil pH
Your soil pH (5.7–6.4) is within Fennel's preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Adams County is excellent for Fennel — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.3%) — Fennel will thrive.
How to Plant Fennel
Succession Planting Fennel
Sow every 6.9 weeks. Last sowing by Jul 05 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Fennel
Fennel needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Fennel Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.7" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | — | 1.4" | 0" | ❄️ Dormant |
| May | 2.6" | 0.8" | 1.8" | 🚿 Regular watering |
| Jun | 2.6" | 0.6" | 2" | 🚿 Regular watering |
| Jul | 2.6" | 0.3" | 2.3" | 🚿 Regular watering |
| Aug | 2.6" | 0.4" | 2.2" | 🚿 Regular watering |
| Sep | 2.6" | 0.6" | 2" | 🚿 Regular watering |
| Oct | 2.6" | 1.6" | 1" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Adams County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Fennel 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.
Fennel Planting Timeline — Adams County, WA
Fennel Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 12 | Mar 12 – Mar 26 |
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Harvest | July 23 | Jul 23 – Sep 3 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| 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
0.6"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 5.5–7 · Your soil: ideal
🗺️ USDA Zone
Zone 6b
📆 Growing Season
149 days in Adams County
Growing Tips for Fennel in Adams County
Direct sow Fennel outdoors after May 07 in Adams County when soil has warmed and frost danger has passed.
Common pests for Fennel in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in late summer for fall harvest to reduce bolting. Hill soil around bulbs as they enlarge. Harvest when bulbs are tennis-ball sized before they elongate.
Companion Planting
Good Companions
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Fennel in Other Locations
Frequently Asked Questions
When should I plant Fennel in Adams County, WA?
Adams County is in Zone 6b with an average last frost of May 7. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.
What planting zone is Adams County, WA?
Adams County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 7 and first fall frost is October 3.
Plan Your Garden with Confidence
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