When to Plant Microgreens in Summit County, CO
Microgreens are young seedlings of vegetables and herbs harvested at the cotyledon or first true leaf stage. They pack concentrated flavors and nutrients in a tiny package.
Summit County, Colorado is in USDA Zone 4a. The average last spring frost is June 16 and the first fall frost is September 4, giving you a growing season of approximately 80 days.
At an elevation of 7,005 feet, Summit County receives approximately 17.5 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Microgreens to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Microgreens successfully. Mulch heavily to conserve soil moisture.
Summit County Soil Profile
Soil Type
Loam
Soil pH
6.8-8
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 Summit County
How your county's soil matches Microgreens's growing requirements.
Soil pH
Your soil pH (6.8–8.0) is more alkaline than Microgreens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Summit County is excellent for Microgreens — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Microgreens.
Organic Matter
Organic matter is moderate (2.1%). Annual compost additions will help Microgreens.
How to Plant Microgreens
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Microgreens
Sow every 0.7 weeks. Last sowing by Aug 14 to harvest before frost.
For a dedicated fall crop, sow by Jun 12.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Microgreens
Microgreens needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Microgreens Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 1.7" | 0" | ❄️ Dormant |
| May | — | 1.8" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Jul | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Aug | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.2" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Summit County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Microgreens 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.
Microgreens Planting Timeline — Summit County, CO
Microgreens Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 5 | May 5 – May 19 |
| Transplant Outdoors | June 16 | Jun 16 – Jun 30 |
| Direct Sow | June 9 | Jun 9 – Jun 30 |
| Harvest | June 23 | Jun 23 – Jul 21 |
| Fall Sowing | June 12 | Jun 12 – Jun 26 |
Plant 0.5" deep · 2" apart · Rows 6" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow Fall Sowing Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
7–21 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 4a
📆 Growing Season
80 days in Summit County
Growing Tips for Microgreens in Summit County
Direct sow Microgreens outdoors after June 16 in Summit County when soil has warmed and frost danger has passed.
Your generous 80.0-day season in Summit County allows multiple plantings of Microgreens. Sow every 3.0 days for continuous harvest.
Summit County receives only 18" of rain annually. Microgreens needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Sow seeds densely on shallow trays of moist growing medium. Cover until germination, then provide light. Harvest with scissors when 1-3 inches tall. Grow year-round indoors.
Microgreens in Other Locations
Frequently Asked Questions
When should I plant Microgreens in Summit County, CO?
Summit County is in Zone 4a with an average last frost of June 16. Plan your Microgreens planting based on this frost date — see the calendar above for exact timing.
What planting zone is Summit County, CO?
Summit County, Colorado is in USDA Hardiness Zone 4a. The average last spring frost is June 16 and first fall frost is September 4.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Summit County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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