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When to Plant Lentils in Stillwater County, MT

Stillwater County, Montana Zone 5a May

What to do in May

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

Avg. last frost May 22
Avg. first frost September 22
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Time to transplant lentils

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Sow lentils where they'll grow

    Your soil is 36°F — warm enough for these to germinate without babying.

Get ahead of June
  • Starting indoors: lentils

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Lentils are an ancient pulse crop producing small, lens-shaped seeds packed with protein and iron. They grow on short, bushy plants and are surprisingly easy to cultivate.

Stillwater County, Montana is in USDA Zone 5a. The average last spring frost is May 22 and the first fall frost is September 22, giving you a growing season of approximately 123 days.

At an elevation of 6,319 feet, Stillwater County receives approximately 16.6 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Lentils to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Lentils successfully. Mulch heavily to conserve soil moisture.

Stillwater County, MT (Zone 5a) Short season
123 days
Last Spring Frost May 22
123 growing days
First Fall Frost September 22
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Stillwater County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Aug 4 – Sep 15
Recommended (50%) ✗ May not fit
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Aug 14 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jun 10 🍅 Harvest: Sep 2 – Oct 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 Stillwater County

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

Soil pH

Your soil pH (6.3–7.8) is within Lentils's preferred range (6.0–8.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Lentils.

How to Plant Lentils

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.6″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 44 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Lentils

Lentils needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Lentils Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.8" 0" ❄️ Dormant
May 2.6" 2" 0.6" 💧 Light watering
Jun 2.6" 1.1" 1.5" 🚿 Regular watering
Jul 2.6" 1.4" 1.2" 💧 Light watering
Aug 2.6" 1.7" 0.9" 💧 Light watering
Sep 2.6" 1.4" 1.2" 💧 Light watering
Oct 1.4" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Stillwater County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Lentils 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.

Lentils needs ~1,164 GDD — county provides 1,506 GDD Good fit

Lentils Planting Timeline — Stillwater County, MT

Lentils Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 8 May 8 – May 29
Harvest August 14 Aug 14 – Sep 25
Fall Sowing July 14 Jul 14 – Jul 28

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Only during dry spells

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

123 days in Stillwater County

Growing Tips for Lentils in Stillwater County

Direct sow Lentils outdoors after May 22 in Stillwater County when soil has warmed and frost danger has passed.

Your 123.0-day growing season in Stillwater County is tight for Lentils (80.0-110.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Lentils in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring as lentils tolerate frost. Provide short supports as plants tend to lodge. Harvest when lower pods turn brown. Pull entire plants and dry in bundles.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lentils in Stillwater County, MT?

Stillwater County is in Zone 5a with an average last frost of May 22. Plan your Lentils planting based on this frost date — see the calendar above for exact timing.

What planting zone is Stillwater County, MT?

Stillwater County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 22 and first fall frost is September 22.

🌱

Your Stillwater County Garden Planner — Free

A 24-page printable planner built for Stillwater 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.

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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 Stillwater 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.