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When to Plant Ageratum in Divide County, ND

Divide County, North Dakota Zone 4a June

June in the garden — Divide County, North Dakota

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Divide County, North Dakota.

Avg. last frost May 15
Avg. first frost September 20
Soil temp (4") 59°F
Watering High
Pest pressure Moderate
Daylight 15.9 hrs
Get ahead of July
  • Starting indoors: ageratum
  • First harvests: ageratum

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Ageratum (Ageratum houstonianum), the floss flower, produces clusters of fluffy, powder-puff blooms in the rare sky-blue and lavender tones difficult to find among warm-season annuals. Compact mounding habit makes it ideal as a front-of-border edging plant. Blooms from early summer through fall with minimal deadheading; heat and humidity tolerant once established.

Divide County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 20, giving you a growing season of approximately 128 days.

At an elevation of 994 feet, Divide County receives approximately 20.5 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Divide County, ND (Zone 4a) Short season
128 days
Last Spring Frost May 15
128 growing days
First Fall Frost September 20

Divide County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 17 Transplant: May 19 🌸 Bloom: Jul 14 – Sep 22
Recommended (50%) ✗ May not fit
Start indoors: Mar 20 Transplant: May 22 🌸 Bloom: Jul 17 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: Apr 1 Transplant: Jun 3 🌸 Bloom: Jul 29 – Oct 7

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 Divide County

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

Soil pH

Your soil pH (6.2–7.6) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

2
successive plantings in your 128-day season

Sow every 6.9 weeks. Last sowing by Jul 07 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 447 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Ageratum

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

Month Ageratum Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 2.8" 1.5" 💧 Light watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 2.1" 2.2" 🚿 Regular watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

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

Ageratum 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.

Ageratum needs ~624 GDD — county provides 1,184 GDD Excellent fit

Ageratum Planting Timeline — Divide County, ND

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 22 May 22 – Jun 12
Bloom July 17 Jul 17 – Sep 25

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

128 days in Divide County

Growing Tips for Ageratum in Divide County

Direct sow Ageratum outdoors after May 15 in Divide County when soil has warmed and frost danger has passed.

Common pests for Ageratum in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

Divide County receives only 20" of rain annually. Ageratum 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 — do not cover seed; it needs light to germinate. Can be direct-sown after last frost once soil warms to 60°F. Transplant or thin to proper spacing after frost danger passes. Deadheading isn't strictly required but tidying spent clusters improves appearance. Provide consistent moisture; drought causes premature setting. Avoid deep shade — blooms best in full sun to light afternoon shade.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Ageratum in Divide County, ND?

Divide County is in Zone 4a with an average last frost of May 15. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Divide County, ND?

Divide County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 20.

🌱

Your Divide County Garden Planner — Free

A 22-page printable planner built for Divide 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 Divide County, ND. Local conditions may vary. Last updated: June 2026.

Sources & credits

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