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When to plant Ageratum in Bristol County, MA

Bristol County sits in USDA Zone 7a. Plant Ageratum between April 26 (after last frost on April 26) and May 17.

When to Plant Ageratum in Bristol County, MA

Bristol County, Massachusetts Zone 7a June

Your June game plan for Bristol County, Massachusetts

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

Avg. last frost April 26
Avg. first frost October 17
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 15 hrs
  1. Fire up the seed-starting tray: ageratum

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

  2. Collect ageratum at their peak

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

July will be here before you know it — start on
  • 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.

Bristol County, Massachusetts is in USDA Zone 7a. The average last spring frost is April 26 and the first fall frost is October 17, giving you a growing season of approximately 174 days.

At an elevation of 833 feet, Bristol County receives approximately 47.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Bristol County, MA (Zone 7a) Moderate season
174 days
Last Spring Frost April 26
174 growing days
First Fall Frost October 17

Bristol County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Start indoors: Mar 8 Transplant: Apr 19 🌸 Bloom: Jun 14 – Oct 4
Recommended (50%) ✓ Fits season (6 days to spare)
Start indoors: Mar 15 Transplant: Apr 26 🌸 Bloom: Jun 21 – Oct 11
Safe Start (90%) ✓ Fits season (3 days to spare)
Start indoors: Apr 2 Transplant: May 14 🌸 Bloom: Jul 9 – Oct 29

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 Bristol County

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

Soil pH

Your soil pH (5.1–6.7) is more acidic than Ageratum prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 174-day season

Sow every 6.9 weeks. Last sowing by Aug 03 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 3.8" 0" ❄️ Dormant
Feb 2.9" 0" ❄️ Dormant
Mar 3.5" 0" ❄️ Dormant
Apr 4.3" 4.4" 0" ✅ Rainfall sufficient
May 4.3" 4" 0.3" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 4.2" 0.1" 💧 Light watering
Oct 4.3" 4.2" 0.1" 💧 Light watering
Nov 3.7" 0" ❄️ Dormant
Dec 3.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Bristol 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 ~1,131 GDD — county provides 2,914 GDD Excellent fit

Ageratum Planting Timeline — Bristol County, MA

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 – Mar 29
Transplant Outdoors April 26 Apr 26 – May 10
Direct Sow April 26 Apr 26 – May 17
Bloom June 21 Jun 21 – Oct 11

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

174 days in Bristol County

Growing Tips for Ageratum in Bristol County

Direct sow Ageratum outdoors after April 26 in Bristol 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 Bristol County, MA?

Bristol County is in Zone 7a with an average last frost of April 26. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bristol County, MA?

Bristol County, Massachusetts is in USDA Hardiness Zone 7a. The average last spring frost is April 26 and first fall frost is October 17.

When should I plant Ageratum in Bristol County, MA?

In Bristol County, MA, plant Ageratum after the last frost (around April 26) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Bristol County, MA for Ageratum?

Bristol County sits in USDA Zone 7a. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Bristol County's climate?

Yes — Ageratum grows well in Bristol County's temperate climate. Bristol County averages a 174-day frost-free season, with last frost around April 26 and first frost around October 17.

🌱

Your Bristol County Garden Planner — Free

A 22-page printable planner built for Bristol County (Zone 7a). 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 Bristol County, MA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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