When to Plant Radish in Solano County, CA
Your May game plan for Solano County, California
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Solano County, California.
Radishes are one of the fastest-growing vegetables, with some varieties ready in under a month. They come in round, elongated, and large winter types.
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 Radish may need afternoon shade and extra watering during peak heat.
Solano County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.3
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 Solano County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (6.8–7.3) is more alkaline than Radish prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Solano County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Radish.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Radish.
How to Plant Radish
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Radish
Sow every 2.4 weeks. Last sowing by Oct 29 to harvest before frost.
For a dedicated fall crop, sow by Oct 08.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Radish
Radish 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 | Radish Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 8.9" | 0" | ❄️ Dormant |
| Feb | 2.2" | 8.4" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 6.6" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Jun | 2.2" | 0.2" | 2" | 🚿 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" | 1.9" | 0.3" | 💧 Light watering |
| Nov | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Dec | 2.2" | 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.
Radish 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.
Radish Planting Timeline — Solano County, CA
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | January 19 | Jan 19 – Feb 9 |
| Harvest | February 16 | Feb 16 – Mar 9 |
| Fall Sowing | October 8 | Oct 8 – Oct 22 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Direct Sow |
| February | Direct Sow Harvest |
| March | Harvest |
| April | — |
| May | — |
| June | — |
| 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
22–35 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
297 days in Solano County
Growing Tips for Radish in Solano County
Direct sow Radish outdoors after February 09 in Solano County when soil has warmed and frost danger has passed.
Summer highs in Solano County reach 95°F — grow Radish as a spring or fall crop. Use shade cloth if planting in summer.
Your generous 298.0-day season in Solano County allows multiple plantings of Radish. Sow every 11.0 days for continuous harvest.
Common pests for Radish in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow every 1-2 weeks for continuous harvest. Do not transplant. Harvest spring radishes promptly to prevent them from becoming pithy and hot.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Radish in Other Locations
Frequently Asked Questions
When should I plant Radish in Solano County, CA?
Solano County is in Zone 9b with an average last frost of February 9. Plan your Radish 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.
Your Solano County Garden Planner — Free
A 24-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.