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When to plant Tomatoes in Cascade County, MT

Cascade County sits in cold Zone 4b. Plant Tomatoes June 2–June 23 for the single annual harvest; the September 21 first frost closes the window.

When to Plant Tomatoes in Cascade County, MT

Tomatoes
Cascade County, Montana Zone 4b June

June in the garden — Cascade County, Montana

Each item below is timed to Cascade County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 19
Avg. first frost September 21
Soil temp (4") 44°F
Watering High
Pest pressure High
Daylight 15.7 hrs
  1. Harden off and plant tomatoes

    Your last frost (May 19) has passed. These warm-season crops can handle outdoor soil now.

  2. Scatter tomatoes into prepared beds

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

A few tasks this June that'll pay off in July
  • Starting indoors: tomatoes

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Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

Cascade County, Montana is in USDA Zone 4b. The average last spring frost is May 19 and the first fall frost is September 21, giving you a growing season of approximately 125 days.

At an elevation of 6,585 feet, Cascade County receives approximately 21.8 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Tomatoes to ensure they mature before fall.

Cascade County, MT (Zone 4b) Short season
125 days
Last Spring Frost May 19
125 growing days
First Fall Frost September 21

Cascade County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.2

Drainage

Well Drained

Tomatoes Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 10 Transplant: Jun 2 🍅 Harvest: Aug 4 – Oct 13
Recommended (50%) ✗ May not fit
Start indoors: Mar 17 Transplant: Jun 9 🍅 Harvest: Aug 11 – Oct 20
Safe Start (90%) ✗ May not fit
Start indoors: Apr 10 Transplant: Jul 3 🍅 Harvest: Sep 4 – Nov 13

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 Cascade County

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

Soil pH

Your soil pH (6.8–8.2) is more alkaline than Tomatoes prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Tomatoes.

Organic Matter

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

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

Succession Planting Tomatoes

2
successive plantings in your 125-day season

Sow every 6.9 weeks. Last sowing by Jun 28 to harvest before frost.

Tomatoes Water Budget

Plant needs
1.2″/week
Rainfall provides
0.7″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,105 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Tomatoes

Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Tomatoes Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 5.2" 2.3" 2.9" 🚿 Regular watering
Jun 5.2" 1.5" 3.7" 🚿 Regular watering
Jul 5.2" 2.1" 3.1" 🚿 Regular watering
Aug 5.2" 2" 3.2" 🚿 Regular watering
Sep 5.2" 1.8" 3.4" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Tomatoes 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.

Tomatoes needs ~888 GDD — county provides 1,531 GDD Excellent fit

Tomatoes Planting Timeline — Cascade County, MT

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 – Mar 31
Transplant Outdoors June 9 Jun 9 – Jun 23
Direct Sow June 2 Jun 2 – Jun 23
Harvest August 11 Aug 11 – Oct 20

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 2-3 times/week

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

125 days in Cascade County

Growing Tips for Tomatoes in Cascade County

Direct sow Tomatoes outdoors after May 19 in Cascade County when soil has warmed and frost danger has passed.

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

Cascade County receives only 22" of rain annually. Tomatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Cascade County

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Cascade County, MT?

Cascade County is in Zone 4b with an average last frost of May 19. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cascade County, MT?

Cascade County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 19 and first fall frost is September 21.

When should I plant Tomatoes in Cascade County, MT?

In Cascade County, MT, plant Tomatoes after the last frost (around May 19) and before the first frost (around September 21). Best results when soil holds above 50°F.

What growing zone is Cascade County, MT for Tomatoes?

Cascade County sits in USDA Zone 4b. Tomatoes grows reliably in zones 3a through 11b, so it's a good fit here.

Can Tomatoes grow in Cascade County's climate?

Yes — Tomatoes grows well in Cascade County's temperate climate. Cascade County averages a 125-day frost-free season, with last frost around May 19 and first frost around September 21.

🌱

Your Cascade County Garden Planner — Free

A 22-page printable planner built for Cascade County (Zone 4b). 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 Cascade County, MT. Local conditions may vary. Last updated: June 2026.

Sources & credits

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