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When to Plant Microgreens in USDA Zone 3b

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.

In Zone 3b, the average last spring frost is around May 10 and the first fall frost is around September 22, giving you a growing season of approximately 135 days.

Zone 3b Short season
135 days
Last Spring Frost May 10
135 growing days
First Fall Frost September 22

Microgreens Planting Timeline — Zone 3b

Where Is USDA Zone 3b?

The map below highlights the states that contain Zone 3b. Click any state to see the Microgreens planting schedule for that location.

Prints a clean, ink-friendly version without maps or navigation.

Microgreens Planting Calendar — Zone 3b

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest May 17 May 17 – Jun 14
Fall Sowing June 30 Jun 30 – Jul 14

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

Month-by-Month Timeline

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

Free Zone 3b Planting Calendar PDF

Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 3b with start dates, transplant windows, and harvest times.

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Growing Conditions

Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

Days to Maturity

7–21 days

Soil pH

6 – 7

Zone Temperature Range

-35°F to -30°F average annual minimum

Growing Season

135 days (Zone 3b average)

Planting Specifications

Planting Depth0.5 inches
Plant Spacing2 inches apart
Row Spacing6 inches between rows

Succession Planting Microgreens in Zone 3b

26
successive plantings in Zone 3b's ~135-day season

Sow every 0.7 weeks for continuous harvest throughout the season.

Growing Tips for Microgreens in Zone 3b

Zone 3b has a short growing season (~135 days). Start Microgreens indoors early and use season-extension techniques like row covers and cold frames.

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.

Saving Microgreens Seeds

Recommended for Your Garden

💡
LED Grow Lights $25-60

Full-spectrum LED lights for starting seeds indoors when daylight is limited.

🔥
Seedling Heat Mat $15-35

Warm soil for faster germination of heat-loving crops like tomatoes and peppers.

🪡
Floating Row Covers $12-30

Protect plants from frost, wind, and pests while letting light and water through.

Frequently Asked Questions

When should I plant Microgreens in Zone 3b?

In Zone 3b, plan your Microgreens planting around the average last frost date of May 10. Start seeds indoors around March 29. Direct sow outdoors around May 3. Transplant seedlings around May 10.

Can Microgreens grow in Zone 3b?

Yes, Microgreens can grow well in Zone 3b, hardy in USDA zones 1a through 13b. Zone 3b has a growing season of approximately 135 days, which is sufficient for Microgreens (7-21 days to maturity).

When can I harvest Microgreens in Zone 3b?

In Zone 3b, expect to harvest Microgreens from May 17 – June 14. Microgreens takes 7-21 days from planting to harvest.

What is the last frost date for Zone 3b?

The average last spring frost in Zone 3b is around May 10, and the first fall frost is around September 22. This gives a growing season of approximately 135 days. These are 50% probability dates — actual frost dates vary year to year.

🌱

Plan Your Garden with Confidence

Get our free Garden Planner — organize your planting dates for Zone 3b, track your crops, and plan your garden season from seed to harvest.

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Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals, University Cooperative Extension planting guides. Planting dates are estimates based on average frost dates — local conditions may vary. Last updated: April 2026.