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When to plant Ageratum in Phillips County, AR

Ageratum planted in Phillips County between March 7 and March 28 matures in 60–75 days — well before the November 12 first frost.

When to Plant Ageratum in Phillips County, AR

Phillips County, Arkansas Zone 8a July

This month in Phillips County, Arkansas

A quick July briefing for Phillips County, Arkansas gardeners — what's urgent, what's next, and what can wait.

Avg. last frost March 14
Avg. first frost November 12
Soil temp (4") 86°F
Watering Low
Pest pressure High
Daylight 14.1 hrs
  1. Bring in the ageratum

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Before August 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.

Phillips County, Arkansas is in USDA Zone 8a. The average last spring frost is March 14 and the first fall frost is November 12, giving you a growing season of approximately 243 days.

At an elevation of 678 feet, Phillips County receives approximately 50 inches of rainfall annually with predominantly silt loam soil. Summer highs average 93°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Phillips County, AR (Zone 8a) Long season
243 days
Last Spring Frost March 14
243 growing days
First Fall Frost November 12

Phillips County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (50 days to spare)
Start indoors: Jan 26 Transplant: Mar 2 🌸 Bloom: Apr 27 – Sep 14
Recommended (50%) ✓ Fits season (54 days to spare)
Start indoors: Jan 31 Transplant: Mar 7 🌸 Bloom: May 2 – Sep 19
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Feb 24 Transplant: Mar 31 🌸 Bloom: May 26 – Oct 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 Phillips County

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

Soil pH

Your soil pH (5.6–6.7) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 243-day season

Sow every 6.9 weeks. Last sowing by Aug 29 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 352 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 4.4" 0" ❄️ Dormant
Feb 4" 0" ❄️ Dormant
Mar 4.3" 5.5" 0" ✅ Rainfall sufficient
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 5.2" 0" ✅ Rainfall sufficient
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 4.3" 3.6" 0.7" 💧 Light watering
Dec 4.2" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Phillips 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 ~1,333 GDD — county provides 4,799 GDD Excellent fit

Ageratum Planting Timeline — Phillips County, AR

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 31 Jan 31 – Feb 14
Transplant Outdoors March 7 Mar 7 – Mar 21
Direct Sow March 7 Mar 7 – Mar 28
Bloom May 2 May 2 – Sep 19

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Start Indoors
March Transplant Outdoors Direct Sow
April
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 8a

📆 Growing Season

243 days in Phillips County

Growing Tips for Ageratum in Phillips County

Direct sow Ageratum outdoors after March 14 in Phillips 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 Phillips County, AR?

Phillips County is in Zone 8a with an average last frost of March 14. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Phillips County, AR?

Phillips County, Arkansas is in USDA Hardiness Zone 8a. The average last spring frost is March 14 and first fall frost is November 12.

When should I plant Ageratum in Phillips County, AR?

In Phillips County, AR, plant Ageratum after the last frost (around March 14) and before the first frost (around November 12). Best results when soil holds above 50°F.

What growing zone is Phillips County, AR for Ageratum?

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

Can Ageratum grow in Phillips County's climate?

Yes — Ageratum grows well in Phillips County's temperate climate. Phillips County averages a 243-day frost-free season, with last frost around March 14 and first frost around November 12.

🌱

Your Phillips County Garden Planner — Free

A 22-page printable planner built for Phillips County (Zone 8a). 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 Phillips County, AR. Local conditions may vary. Last updated: July 2026.

Sources & credits

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