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When to Plant Ageratum in Logan County, ND

Logan County, North Dakota Zone 4a July

July in the garden — Logan County, North Dakota

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

Avg. last frost May 13
Avg. first frost September 28
Soil temp (4") 72°F
Watering Moderate
Pest pressure High
Daylight 15.3 hrs
  1. Sow ageratum in trays indoors

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. Basket week: ageratum

    If you can't use it all right away, check the food-preservation section of your planner.

Coming up in August — start thinking about
  • 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.

Logan County, North Dakota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 28, giving you a growing season of approximately 138 days.

At an elevation of 1,073 feet, Logan County receives approximately 25.2 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Logan County, ND (Zone 4a) Short season
138 days
Last Spring Frost May 13
138 growing days
First Fall Frost September 28

Logan County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 12 Transplant: May 14 🌸 Bloom: Jul 9 – Sep 17
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Mar 18 Transplant: May 20 🌸 Bloom: Jul 15 – Sep 23
Safe Start (90%) ✓ Fits season (2 days to spare)
Start indoors: Mar 31 Transplant: Jun 2 🌸 Bloom: Jul 28 – Oct 6

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 Logan County

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

Soil pH

Your soil pH (6.5–7.7) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

2
successive plantings in your 138-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 343 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 0.6" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 3.9" 0.4" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 2.5" 1.8" 💧 Light watering
Oct 1.5" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Logan 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 ~776 GDD — county provides 1,587 GDD Excellent fit

Ageratum Planting Timeline — Logan County, ND

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 – Apr 1
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 20 May 20 – Jun 10
Bloom July 15 Jul 15 – Sep 23

· 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 · Only during dry spells

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4a

📆 Growing Season

138 days in Logan County

Growing Tips for Ageratum in Logan County

Direct sow Ageratum outdoors after May 13 in Logan 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.

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 Logan County, ND?

Logan County is in Zone 4a with an average last frost of May 13. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Logan County, ND?

Logan County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 28.

🌱

Your Logan County Garden Planner — Free

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

Sources & credits

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