When to Plant Dill in Sonoma County, CA
Dill is a feathery annual herb with aromatic leaves and seeds. Its fine foliage and umbrella-shaped flower heads attract beneficial insects to the garden.
Sonoma County, California is in USDA Zone 9a. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.
At an elevation of 91 feet, Sonoma County receives approximately 31.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 90°F, providing good warmth for Dill during the growing season. Sandy soil warms quickly in spring — great for early planting — but Dill will need more frequent watering and organic matter to retain nutrients.
Sonoma County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.9-7
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 Sonoma County
How your county's soil matches Dill's growing requirements.
Soil pH
Your soil pH (5.9–7.0) is within Dill's preferred range (5.5–7.0).
Soil Texture
Sandy soil in Sonoma County warms quickly in spring but drains fast. Dill will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Dill.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Dill.
How to Plant Dill
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Dill
Sow every 4.6 weeks. Last sowing by Sep 27 to harvest before frost.
For a dedicated fall crop, sow by Oct 01.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Dill
Dill needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Dill Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.2" | 0" | ❄️ Dormant |
| Feb | 2.2" | 6.8" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 5.2" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 2.3" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Jun | 2.2" | 0.1" | 2.1" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Oct | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Nov | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Dec | — | 5.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Sonoma County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Dill 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.
Dill Planting Timeline — Sonoma County, CA
Dill Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 29 | Jan 29 – Feb 12 |
| Transplant Outdoors | February 19 | Feb 19 – Mar 5 |
| Direct Sow | February 5 | Feb 5 – Feb 26 |
| Harvest | April 2 | Apr 2 – Jun 4 |
| Fall Sowing | October 1 | Oct 1 – Oct 15 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 5.5–7 · Your soil: ideal
🗺️ USDA Zone
Zone 9a
📆 Growing Season
273 days in Sonoma County
Growing Tips for Dill in Sonoma County
Direct sow Dill outdoors after February 26 in Sonoma County when soil has warmed and frost danger has passed.
Sandy soil in Sonoma County dries quickly — mulch Dill with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Your generous 274.0-day season in Sonoma County allows multiple plantings of Dill. Sow every 20.0 days for continuous harvest.
Common pests for Dill 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 spring as dill has a taproot and dislikes transplanting. Succession sow for continuous leaf harvest. Allow some plants to flower for seeds and to attract beneficial insects.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Dill in Other Locations
Frequently Asked Questions
When should I plant Dill in Sonoma County, CA?
Sonoma County is in Zone 9a with an average last frost of February 26. Plan your Dill planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sonoma County, CA?
Sonoma County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 26 and first fall frost is November 26.
Plan Your Garden with Confidence
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