When to Plant Radish in San Bernardino County, CA
Your May planting checklist for San Bernardino County, California
We've pulled the most time-sensitive tasks for San Bernardino County, California this May and put them front and centre. Tackle them in order.
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.
San Bernardino County, California is in USDA Zone 10a. The average last spring frost is February 24 and the first fall frost is November 25, giving you a growing season of approximately 274 days.
At an elevation of 1,012 feet, San Bernardino County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 97°F, so Radish may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Radish successfully. Mulch heavily to conserve soil moisture.
San Bernardino County Soil Profile
Soil Type
Loam
Soil pH
5.9-7.2
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 San Bernardino County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (5.9–7.2) overlaps with Radish's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in San Bernardino County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). 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 21 to harvest before frost.
For a dedicated fall crop, sow by Sep 30.
Plant Water Budget
Water stress score is 10/10 — 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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | 2.2" | 3.8" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| May | 2.2" | 0.5" | 1.7" | 🚿 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" | 0.2" | 2" | 🚿 Regular watering |
| Oct | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Nov | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in San Bernardino 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 — San Bernardino County, CA
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | February 3 | Feb 3 – Feb 24 |
| Harvest | March 3 | Mar 3 – Mar 24 |
| Fall Sowing | September 30 | Sep 30 – Oct 14 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Direct Sow |
| March | Harvest |
| April | — |
| May | — |
| June | — |
| July | — |
| August | — |
| September | Fall Sowing |
| 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: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
274 days in San Bernardino County
Growing Tips for Radish in San Bernardino County
Direct sow Radish outdoors after February 24 in San Bernardino County when soil has warmed and frost danger has passed.
Summer highs in San Bernardino County reach 97°F — grow Radish as a spring or fall crop. Use shade cloth if planting in summer.
Your generous 275.0-day season in San Bernardino 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 San Bernardino County, CA?
San Bernardino County is in Zone 10a with an average last frost of February 24. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Bernardino County, CA?
San Bernardino County, California is in USDA Hardiness Zone 10a. The average last spring frost is February 24 and first fall frost is November 25.
Your San Bernardino County Garden Planner — Free
A 24-page printable planner built for San Bernardino County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.