When to plant Basil in Douglas County, CO
Douglas County sits in cold Zone 5b. Plant Basil May 29–June 19 for the single annual harvest; the September 20 first frost closes the window.
When to Plant Basil in Douglas County, CO
Your June gardening checklist
Your garden in Douglas County, Colorado is working on a schedule, even when you're not. Here's where you should be this June.
-
Move basil into the garden
Frost risk is low now in Douglas County, Colorado. If you've been covering beds overnight, you can stop.
Get ahead of July
- Starting indoors: basil
- First harvests: basil
Basil is a fragrant warm-season herb essential to Italian and Thai cuisines. It comes in many varieties including sweet, Thai, purple, and lemon types.
Douglas County, Colorado is in USDA Zone 5b. The average last spring frost is May 22 and the first fall frost is September 20, giving you a growing season of approximately 121 days.
At an elevation of 7,421 feet, Douglas County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Basil during the growing season. With low rainfall, drip irrigation is essential for growing Basil successfully. Mulch heavily to conserve soil moisture.
Douglas County Soil Profile
Soil Type
Loam
Soil pH
6.7-8.4
Drainage
Well Drained
Basil 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 Douglas County
How your county's soil matches Basil's growing requirements.
Soil pH
Your soil pH (6.7–8.4) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Douglas County is excellent for Basil — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Basil.
How to Plant Basil
Succession Planting Basil
Sow every 5.7 weeks. Last sowing by Jul 07 to harvest before frost.
Basil Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Basil
Basil needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Basil Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.1" | 0" | ❄️ Dormant |
| Apr | — | 1.3" | 0" | ❄️ Dormant |
| May | 2.6" | 1.4" | 1.2" | 💧 Light watering |
| Jun | 2.6" | 1" | 1.6" | 🚿 Regular watering |
| Jul | 2.6" | 1" | 1.6" | 🚿 Regular watering |
| Aug | 2.6" | 1.4" | 1.2" | 💧 Light watering |
| Sep | 2.6" | 1.1" | 1.5" | 🚿 Regular watering |
| Oct | — | 1.1" | 0" | ❄️ Dormant |
| Nov | — | 1" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Douglas County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Basil 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.
Basil Planting Timeline — Douglas County, CO
Basil Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 3 | Apr 3 – Apr 17 |
| Transplant Outdoors | June 5 | Jun 5 – Jun 19 |
| Direct Sow | May 29 | May 29 – Jun 19 |
| Harvest | July 31 | Jul 31 – Oct 2 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.6"/week · Only during dry spells
📅 Days to Maturity
50–75 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
121 days in Douglas County
Growing Tips for Basil in Douglas County
Direct sow Basil outdoors after May 22 in Douglas County when soil has warmed and frost danger has passed.
General growing tips
Start seeds indoors or direct sow after last frost. Pinch flower buds to extend leaf production. Harvest leaves from the top down, cutting just above a leaf pair.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 150 ft between varieties. Different basil species can cross.
Basil in Other Locations
Frequently Asked Questions
When should I plant Basil in Douglas County, CO?
Douglas County is in Zone 5b with an average last frost of May 22. Plan your Basil planting based on this frost date — see the calendar above for exact timing.
What planting zone is Douglas County, CO?
Douglas County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 22 and first fall frost is September 20.
When should I plant Basil in Douglas County, CO?
In Douglas County, CO, plant Basil after the last frost (around May 22) and before the first frost (around September 20). Best results when soil holds above 50°F.
What growing zone is Douglas County, CO for Basil?
Douglas County sits in USDA Zone 5b. Basil grows reliably in zones 4a through 11b, so it's a good fit here.
Can Basil grow in Douglas County's climate?
Yes — Basil grows well in Douglas County's temperate climate. Douglas County averages a 121-day frost-free season, with last frost around May 22 and first frost around September 20.
Your Douglas County Garden Planner — Free
A 22-page printable planner built for Douglas County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.