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When to plant Celery in Solano County, CA

Plant Celery in Solano County after February 9; the prime window is January 19–February 9. A second sowing from October 8 to October 22 extends the harvest into fall.

When to Plant Celery in Solano County, CA

Celery
Solano County, California Zone 9b July

What to do in July

Each item below is timed to Solano County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost February 9
Avg. first frost December 3
Soil temp (4") 95°F
Watering Critical
Pest pressure High
Daylight 14.4 hrs

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Celery is a marshland plant that requires consistent moisture and cool temperatures to produce crisp, flavorful stalks. It is a rewarding but demanding garden crop.

Solano County, California is in USDA Zone 9b. The average last spring frost is February 9 and the first fall frost is December 3, giving you a growing season of approximately 297 days.

At an elevation of 376 feet, Solano County receives approximately 40.4 inches of rainfall annually with predominantly loam soil. Summer highs average 95°F, so Celery may need afternoon shade and extra watering during peak heat.

Solano County, CA (Zone 9b) Year-round
297 days
Last Spring Frost February 9
297 growing days
First Fall Frost December 3

Solano County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.3

Drainage

Well Drained

Celery Planting Risk Windows

Early Start (70% safe) ✓ Fits season (165 days to spare)
Start indoors: Dec 28 Transplant: Jan 25 🍅 Harvest: Apr 19 – Jun 14
Recommended (50%) ✓ Fits season (157 days to spare)
Start indoors: Jan 12 Transplant: Feb 9 🍅 Harvest: May 4 – Jun 29
Safe Start (90%) ✓ Fits season (141 days to spare)
Start indoors: Feb 13 Transplant: Mar 13 🍅 Harvest: Jun 5 – Jul 31

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 Solano County

How your county's soil matches Celery's growing requirements.

Soil pH

Your soil pH (6.8–7.3) is more alkaline than Celery prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Solano County is excellent for Celery — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Celery is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Celery.

How to Plant Celery

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Celery

4
successive plantings in your 297-day season

Sow every 9.1 weeks. Last sowing by Aug 05 to harvest before frost.

For a dedicated fall crop, sow by Oct 08.

Celery Water Budget

Plant needs
1.3″/week
Rainfall provides
0.6″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 3,566 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Celery

Celery 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 Celery Needs Rainfall You Supplement Action
Jan 8.9" 0" ❄️ Dormant
Feb 5.6" 8.4" 0" ✅ Rainfall sufficient
Mar 5.6" 6.6" 0" ✅ Rainfall sufficient
Apr 5.6" 2.7" 2.9" 🚿 Regular watering
May 5.6" 1" 4.6" 🚿 Regular watering
Jun 5.6" 0.2" 5.4" 🚿 Regular watering
Jul 5.6" 0" 5.6" 🚿 Regular watering
Aug 5.6" 0" 5.6" 🚿 Regular watering
Sep 5.6" 0.4" 5.2" 🚿 Regular watering
Oct 5.6" 1.9" 3.7" 🚿 Regular watering
Nov 5.6" 3.3" 2.3" 💧 Light watering
Dec 5.6" 7.1" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in Solano County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Celery 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.

Celery needs ~2,125 GDD — county provides 6,332 GDD Excellent fit

Celery Planting Timeline — Solano County, CA

Celery Planting Calendar

Activity When Date Range
Start Indoors January 12 Jan 12 – Jan 26
Transplant Outdoors February 9 Feb 9 – Feb 23
Direct Sow January 19 Jan 19 – Feb 9
Harvest May 4 May 4 – Jun 29
Fall Sowing October 8 Oct 8 – Oct 22

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors Direct Sow
February Transplant Outdoors Direct Sow
March
April
May Harvest
June Harvest
July
August
September
October Fall Sowing
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · 2-3 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

297 days in Solano County

Growing Tips for Celery in Solano County

Direct sow Celery outdoors after February 09 in Solano County when soil has warmed and frost danger has passed.

Common pests for Celery in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Keep soil consistently moist and never let it dry out. Blanch stalks by mounding soil or using collars for milder flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Celery in Solano County, CA?

Solano County is in Zone 9b with an average last frost of February 9. Plan your Celery planting based on this frost date — see the calendar above for exact timing.

What planting zone is Solano County, CA?

Solano County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 9 and first fall frost is December 3.

When should I plant Celery in Solano County, CA?

In Solano County, CA, plant Celery after the last frost (around February 9) and before the first frost (around December 3). Best results when soil holds above 50°F.

What growing zone is Solano County, CA for Celery?

Solano County sits in USDA Zone 9b. Celery grows reliably in zones 2a through 10b, so it's a good fit here.

Can Celery grow in Solano County's climate?

Yes — Celery grows well in Solano County's temperate climate. Solano County averages a 298-day frost-free season, with last frost around February 9 and first frost around December 3.

🌱

Your Solano County Garden Planner — Free

A 22-page printable planner built for Solano County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Solano County, CA. Local conditions may vary. Last updated: July 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.