When to Plant Collard Greens in San Juan County, CO
This month in San Juan County, Colorado
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in San Juan County, Colorado.
June will be here before you know it — start on
- Transplants going out: collard greens
- Direct-sowing: collard greens
- Fall sowing: collard greens
Collard greens are a heat-tolerant member of the cabbage family with large, sturdy leaves. They are a Southern staple and one of the most nutritious leafy greens.
San Juan County, Colorado is in USDA Zone 5a. The average last spring frost is June 18 and the first fall frost is September 8, giving you a growing season of approximately 82 days.
At an elevation of 7,539 feet, San Juan County receives approximately 20.1 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Collard Greens to ensure they mature before fall.
San Juan County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
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 Juan County
How your county's soil matches Collard Greens's growing requirements.
Soil pH
Your soil pH (6.3–8.0) is more alkaline than Collard Greens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in San Juan County is excellent for Collard Greens — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Collard Greens.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Collard Greens.
How to Plant Collard Greens
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Collard Greens
Collard Greens needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Collard Greens Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 2" | 0" | ❄️ Dormant |
| May | — | 2.4" | 0" | ❄️ Dormant |
| Jun | 3.5" | 1.6" | 1.9" | 🚿 Regular watering |
| Jul | 3.5" | 2" | 1.5" | 💧 Light watering |
| Aug | 3.5" | 2.3" | 1.2" | 💧 Light watering |
| Sep | 3.5" | 1.6" | 1.9" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in San Juan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Collard Greens 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.
Collard Greens Planting Timeline — San Juan County, CO
Collard Greens Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 14 | May 14 – May 28 |
| Transplant Outdoors | June 18 | Jun 18 – Jul 2 |
| Direct Sow | June 4 | Jun 4 – Jun 25 |
| Harvest | August 13 | Aug 13 – Oct 15 |
| Fall Sowing | June 30 | Jun 30 – Jul 14 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Transplant Outdoors Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Only during dry spells
📅 Days to Maturity
55–75 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
82 days in San Juan County
Growing Tips for Collard Greens in San Juan County
Direct sow Collard Greens outdoors after June 18 in San Juan County when soil has warmed and frost danger has passed.
Your 82.0-day growing season in San Juan County is tight for Collard Greens (55.0-75.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Collard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors or direct sow 4-6 weeks before last frost. Harvest lower leaves first, leaving the growing tip intact. Flavor improves after exposure to frost.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Collard Greens in Other Locations
Frequently Asked Questions
When should I plant Collard Greens in San Juan County, CO?
San Juan County is in Zone 5a with an average last frost of June 18. Plan your Collard Greens planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Juan County, CO?
San Juan County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 18 and first fall frost is September 8.
Your San Juan County Garden Planner — Free
A 24-page printable planner built for San Juan County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.