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When to Plant Microgreens in Ravalli County, MT

Ravalli County, Montana Zone 5b May

Top priorities for Ravalli County, Montana gardeners in May

Here's what deserves your attention in Ravalli County, Montana this month. Everything below is tailored to Zone 5b and timed around your local frost dates.

Avg. last frost May 21
Avg. first frost September 20
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Get microgreens in the ground

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Put microgreens seeds straight in the ground

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

  3. Harvest microgreens as they ripen

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

To set up a strong June, finish these tasks
  • Starting indoors: microgreens
  • First harvests: microgreens

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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.

Ravalli County, Montana is in USDA Zone 5b. The average last spring frost is May 21 and the first fall frost is September 20, giving you a growing season of approximately 122 days.

At an elevation of 7,813 feet, Ravalli County receives approximately 15.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84°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.

Ravalli County, MT (Zone 5b) Short season
122 days
Last Spring Frost May 21
122 growing days
First Fall Frost September 20
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Ravalli County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (88 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: May 19 – Jun 16
Recommended (50%) ✓ Fits season (87 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: May 28 – Jun 25
Safe Start (90%) ✓ Fits season (86 days to spare)
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Jun 16 – Jul 14

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 Ravalli County

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

Soil pH

Your soil pH (6.5–7.8) is more alkaline than Microgreens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Ravalli County is excellent for Microgreens — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.8%). 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

24
successive plantings in your 122-day season

Sow every 0.7 weeks. Last sowing by Aug 30 to harvest before frost.

For a dedicated fall crop, sow by Jul 12.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 626 gal / 100 sq ft
Drought risk

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 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 4.3" 1.8" 2.5" 🚿 Regular watering
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 1.5" 2.8" 🚿 Regular watering
Aug 4.3" 1.6" 2.7" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Ravalli 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 needs ~182 GDD — county provides 1,586 GDD Excellent fit

Microgreens Planting Timeline — Ravalli County, MT

Microgreens Planting Calendar

Activity When Date Range
Start Indoors April 16 Apr 16 – Apr 30
Transplant Outdoors May 21 May 21 – Jun 4
Direct Sow May 7 May 7 – May 28
Harvest May 28 May 28 – Jun 25
Fall Sowing July 12 Jul 12 – Jul 26

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow Harvest
June Transplant Outdoors Harvest
July Fall Sowing
August
September
October
November
December
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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 5b

📆 Growing Season

122 days in Ravalli County

Growing Tips for Microgreens in Ravalli County

Direct sow Microgreens outdoors after May 21 in Ravalli County when soil has warmed and frost danger has passed.

Your generous 122.0-day season in Ravalli County allows multiple plantings of Microgreens. Sow every 3.0 days for continuous harvest.

Ravalli County receives only 15" 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.

Frequently Asked Questions

When should I plant Microgreens in Ravalli County, MT?

Ravalli County is in Zone 5b with an average last frost of May 21. Plan your Microgreens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ravalli County, MT?

Ravalli County, Montana is in USDA Hardiness Zone 5b. The average last spring frost is May 21 and first fall frost is September 20.

🌱

Your Ravalli County Garden Planner — Free

A 24-page printable planner built for Ravalli 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.

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

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.