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When to plant Ageratum in Simpson County, MS

Spring Ageratum in Simpson County goes in February 24–March 17, once nighttime temps stop dipping near freezing.

When to Plant Ageratum in Simpson County, MS

Simpson County, Mississippi Zone 8b June

June to-do list for Simpson County, Mississippi

June is a pivotal month for Simpson County, Mississippi gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost March 10
Avg. first frost November 15
Soil temp (4") 85°F
Watering Low
Pest pressure High
Daylight 14.1 hrs
  1. Pick ageratum

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

Before July arrives, get these ready
  • 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.

Simpson County, Mississippi is in USDA Zone 8b. The average last spring frost is March 10 and the first fall frost is November 15, giving you a growing season of approximately 250 days.

At an elevation of 90 feet, Simpson County receives approximately 48.4 inches of rainfall annually with predominantly clay loam soil. Summer highs average 97°F, so Ageratum may need afternoon shade and extra watering during peak heat. Clay soil retains moisture well for Ageratum, but amend with compost to improve drainage and prevent root rot.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Simpson County, MS (Zone 8b) Long season
250 days
Last Spring Frost March 10
250 growing days
First Fall Frost November 15

Simpson County Soil Profile

Soil Type

Clay Loam

Soil pH

5.6-6.8

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (55 days to spare)
Start indoors: Jan 20 Transplant: Feb 17 🌸 Bloom: Apr 14 – Sep 15
Recommended (50%) ✓ Fits season (54 days to spare)
Start indoors: Jan 27 Transplant: Feb 24 🌸 Bloom: Apr 21 – Sep 22
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Feb 16 Transplant: Mar 16 🌸 Bloom: May 11 – Oct 12

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 Simpson County

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

Soil pH

Your soil pH (5.6–6.8) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 250-day season

Sow every 6.9 weeks. Last sowing by Sep 01 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 499 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 4.3" 0" ❄️ Dormant
Feb 4" 0" ❄️ Dormant
Mar 4.3" 4.3" 0" ✅ Rainfall sufficient
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.9" 0" ✅ Rainfall sufficient
Jul 4.3" 4.8" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 4.3" 3.4" 0.9" 💧 Light watering
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Simpson 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 ~1,536 GDD — county provides 5,687 GDD Excellent fit

Ageratum Planting Timeline — Simpson County, MS

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 27 Jan 27 – Feb 10
Transplant Outdoors February 24 Feb 24 – Mar 10
Direct Sow February 24 Feb 24 – Mar 17
Bloom April 21 Apr 21 – Sep 22

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Start Indoors Transplant Outdoors Direct Sow
March Transplant Outdoors Direct Sow
April Bloom
May Bloom
June Bloom
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: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

250 days in Simpson County

Growing Tips for Ageratum in Simpson County

Direct sow Ageratum outdoors after March 10 in Simpson County when soil has warmed and frost danger has passed.

With Simpson County's clay soil (32% clay), work in 3-4 inches of compost before planting Ageratum. Avoid tilling when soil is wet to prevent compaction.

With summer highs reaching 97°F in Simpson County, provide afternoon shade for Ageratum and water deeply in the morning.

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 Simpson County, MS?

Simpson County is in Zone 8b with an average last frost of March 10. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Simpson County, MS?

Simpson County, Mississippi is in USDA Hardiness Zone 8b. The average last spring frost is March 10 and first fall frost is November 15.

When should I plant Ageratum in Simpson County, MS?

In Simpson County, MS, plant Ageratum after the last frost (around March 10) and before the first frost (around November 15). Best results when soil holds above 50°F.

What growing zone is Simpson County, MS for Ageratum?

Simpson County sits in USDA Zone 8b. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Simpson County's climate?

Yes — Ageratum grows well in Simpson County's temperate climate. Simpson County averages a 250-day frost-free season, with last frost around March 10 and first frost around November 15.

🌱

Your Simpson County Garden Planner — Free

A 22-page printable planner built for Simpson County (Zone 8b). 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 Simpson County, MS. 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.