When to Plant Radish in Broomfield County, CO
May in the garden — Broomfield County, Colorado
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
-
Harvest radish as they ripen
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
June will be here before you know it — start on
- First harvests: radish
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.
Broomfield County, Colorado is in USDA Zone 6a. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.
At an elevation of 7,037 feet, Broomfield County receives approximately 13.9 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Radish during the growing season. With low rainfall, drip irrigation is essential for growing Radish successfully. Mulch heavily to conserve soil moisture.
Broomfield County Soil Profile
Soil Type
Loam
Soil pH
6.2-8.2
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 Broomfield County
How your county's soil matches Radish's growing requirements.
Soil pH
Your soil pH (6.2–8.2) is more alkaline than Radish prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Broomfield County is excellent for Radish — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.9%). Annual compost additions will help Radish.
How to Plant Radish
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Radish
Sow every 2.4 weeks. Last sowing by Aug 22 to harvest before frost.
For a dedicated fall crop, sow by Jul 18.
Plant Water Budget
Water stress score is 6/10 — 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 | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 0.7" | 0" | ❄️ Dormant |
| Mar | — | 1.1" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Jun | 2.2" | 0.9" | 1.3" | 🚿 Regular watering |
| Jul | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Aug | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Sep | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Oct | — | 1.2" | 0" | ❄️ Dormant |
| Nov | — | 1" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Broomfield 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 — Broomfield County, CO
Radish Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 30 | Apr 30 – May 21 |
| Harvest | May 28 | May 28 – Jun 18 |
| Fall Sowing | July 18 | Jul 18 – Aug 1 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow Harvest |
| June | Harvest |
| July | Fall Sowing |
| August | Fall Sowing |
| September | — |
| October | — |
| 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 6a
📆 Growing Season
135 days in Broomfield County
Growing Tips for Radish in Broomfield County
Direct sow Radish outdoors after May 14 in Broomfield County when soil has warmed and frost danger has passed.
Your generous 135.0-day season in Broomfield 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 Broomfield County, CO?
Broomfield County is in Zone 6a with an average last frost of May 14. Plan your Radish planting based on this frost date — see the calendar above for exact timing.
What planting zone is Broomfield County, CO?
Broomfield County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is May 14 and first fall frost is September 26.
Your Broomfield County Garden Planner — Free
A 24-page printable planner built for Broomfield County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.