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When to plant Geraniums in Dawson County, MT

Dawson County's short 131-day growing season means one Geraniums planting between May 28 and June 11. No fall crop in Zone 4a.

When to Plant Geraniums in Dawson County, MT

Dawson County, Montana Zone 4a June

This month in Dawson County, Montana

Your Dawson County, Montana garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.

Avg. last frost May 14
Avg. first frost September 22
Soil temp (4") 44°F
Watering High
Pest pressure High
Daylight 15.7 hrs
Looking ahead to July
  • Starting indoors: geraniums

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Geraniums (Pelargonium × hortorum) are tender perennials grown as warm-season annuals throughout North America. Prized for their bold flower clusters, long bloom period, and tolerance of summer heat when planted in well-drained soil, they anchor window boxes, containers, and bed borders from late spring until hard frost. Zones 9b–11b can overwinter plants in the ground.

Dawson County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 22, giving you a growing season of approximately 131 days.

At an elevation of 6,445 feet, Dawson County receives approximately 21.9 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Geraniums to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant Good for cutting Fragrant
Dawson County, MT (Zone 4a) Short season
131 days
Last Spring Frost May 14
131 growing days
First Fall Frost September 22

Dawson County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.2

Drainage

Well Drained

Geraniums Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 22 Transplant: May 24 🌸 Bloom: Aug 2 – Oct 4
Recommended (50%) ✗ May not fit
Start indoors: Feb 26 Transplant: May 28 🌸 Bloom: Aug 6 – Oct 8
Safe Start (90%) ✗ May not fit
Start indoors: Mar 11 Transplant: Jun 10 🌸 Bloom: Aug 19 – Oct 21

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 Dawson County

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

Soil pH

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

Soil Texture

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

Drainage

Drainage is adequate for Geraniums.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Geraniums.

How to Plant Geraniums

0.1"
Planting Depth
12"
Between Plants
14"
Between Rows

Succession Planting Geraniums

2
successive plantings in your 131-day season

Sow every 8 weeks. Last sowing by Jun 14 to harvest before frost.

Geraniums Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 836 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Geraniums

Geraniums needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Geraniums Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.3" 2.8" 1.5" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 2" 2.3" 🚿 Regular watering
Aug 4.3" 2.1" 2.2" 🚿 Regular watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Geraniums 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.

Geraniums needs ~850 GDD — county provides 1,310 GDD Excellent fit

Geraniums Planting Timeline — Dawson County, MT

Geraniums Planting Calendar

Activity When Date Range
Start Indoors February 26 Feb 26 – Mar 12
Transplant Outdoors May 28 May 28 – Jun 11
Bloom August 6 Aug 6 – Oct 8

Plant 0.1" deep · 12" apart · Rows 14" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4a

📆 Growing Season

131 days in Dawson County

Growing Tips for Geraniums in Dawson County

Direct sow Geraniums outdoors after May 14 in Dawson County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 10–12 weeks before last frost — germination is slow and erratic without bottom heat (70–75°F). Transplant after frost danger passes. Geraniums rarely direct-sown; cuttings or transplants are the standard. Deadhead spent umbels weekly to maintain continuous bloom. Let soil dry slightly between waterings to prevent root rot. In zones 10–11 plants may be left in ground year-round or overwintered as houseplants.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Geraniums in Dawson County, MT?

Dawson County is in Zone 4a with an average last frost of May 14. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dawson County, MT?

Dawson County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 22.

When should I plant Geraniums in Dawson County, MT?

In Dawson County, MT, plant Geraniums after the last frost (around May 14) and before the first frost (around September 22). Best results when soil holds above 50°F.

What growing zone is Dawson County, MT for Geraniums?

Dawson County sits in USDA Zone 4a. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.

Can Geraniums grow in Dawson County's climate?

Yes — Geraniums grows well in Dawson County's temperate climate. Dawson County averages a 131-day frost-free season, with last frost around May 14 and first frost around September 22.

🌱

Your Dawson County Garden Planner — Free

A 22-page printable planner built for Dawson County (Zone 4a). 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 Dawson 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.