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When to Plant Microgreens in Rio Blanco 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.

Rio Blanco County, Colorado is in USDA Zone 5a. The average last spring frost is June 2 and the first fall frost is September 17, giving you a growing season of approximately 107 days.

At an elevation of 6,974 feet, Rio Blanco County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Microgreens during the growing season. With low rainfall, drip irrigation is essential for growing Microgreens successfully. Mulch heavily to conserve soil moisture.

Rio Blanco County, CO (Zone 5a) Short season
107 days
Last Spring Frost June 2
107 growing days
First Fall Frost September 17

Rio Blanco County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (77 days to spare)
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: May 26 – Jun 23
Recommended (50%) ✓ Fits season (72 days to spare)
Start indoors: Apr 28 Transplant: Jun 2 🍅 Harvest: Jun 9 – Jul 7
Safe Start (90%) ✓ Fits season (77 days to spare)
Start indoors: May 16 Transplant: Jun 20 🍅 Harvest: Jun 27 – Jul 25

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 Rio Blanco County

How your county's soil matches Microgreens's growing requirements.

Soil pH

Your soil pH (6.4โ€“7.7) is more alkaline than Microgreens prefers (6.0โ€“7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Rio Blanco County is excellent for Microgreens โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Microgreens.

How to Plant Microgreens

0.5"
Planting Depth
2"
Between Plants
6"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Microgreens

21
successive plantings in your 107-day season

Sow every 0.7 weeks. Last sowing by Aug 27 to harvest before frost.

For a dedicated fall crop, sow by Jul 09.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 290 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” 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 โ€” 1.3" 0" โ„๏ธ Dormant
Feb โ€” 1.3" 0" โ„๏ธ Dormant
Mar โ€” 1.8" 0" โ„๏ธ Dormant
Apr โ€” 2" 0" โ„๏ธ Dormant
May โ€” 2.1" 0" โ„๏ธ Dormant
Jun 4.3" 1.3" 3" ๐Ÿšฟ Regular watering
Jul 4.3" 1.4" 2.9" ๐Ÿšฟ Regular watering
Aug 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Sep 4.3" 1.6" 2.7" ๐Ÿšฟ Regular watering
Oct โ€” 1.6" 0" โ„๏ธ Dormant
Nov โ€” 1.5" 0" โ„๏ธ Dormant
Dec โ€” 1.3" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Junโ€“Sep in Rio Blanco County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 needs ~203 GDD — county provides 1,551 GDD Excellent fit

Microgreens Planting Timeline โ€” Rio Blanco County, CO

Microgreens Planting Calendar

Activity When Date Range
Start Indoors April 28 Apr 28 โ€“ May 12
Transplant Outdoors June 2 Jun 2 โ€“ Jun 16
Direct Sow May 19 May 19 โ€“ Jun 9
Harvest June 9 Jun 9 โ€“ Jul 7
Fall Sowing July 9 Jul 9 โ€“ Jul 23

Plant 0.5" deep ยท 2" apart ยท Rows 6" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow Harvest
July Fall Sowing Harvest
August โ€”
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Partial Shade (3-6 hours)

๐Ÿ’ง Water

1"/week ยท 1-2 times/week

๐Ÿ“… Days to Maturity

7โ€“21 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: too_alkaline

๐Ÿ—บ๏ธ USDA Zone

Zone 5a

๐Ÿ“† Growing Season

107 days in Rio Blanco County

Growing Tips for Microgreens in Rio Blanco County

Direct sow Microgreens outdoors after June 02 in Rio Blanco County when soil has warmed and frost danger has passed.

Your generous 107.0-day season in Rio Blanco County allows multiple plantings of Microgreens. Sow every 3.0 days for continuous harvest.

Rio Blanco County receives only 19" of rain annually. Microgreens needs consistent moisture โ€” 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.

Frequently Asked Questions

When should I plant Microgreens in Rio Blanco County, CO?

Rio Blanco County is in Zone 5a with an average last frost of June 2. Plan your Microgreens planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Rio Blanco County, CO?

Rio Blanco County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 2 and first fall frost is September 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Rio Blanco County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Rio Blanco County, CO. Local conditions may vary. Last updated: April 2026.