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When to plant Ageratum in Calaveras County County,

For Calaveras County County, gardeners: plant Ageratum March 25 through April 15 once soil reads 50°F.

When to Plant Ageratum in Calaveras County, CA

Calaveras County, California Zone 9a June

Your June planting checklist for Calaveras County, California

We've pulled the most time-sensitive tasks for Calaveras County, California this June and put them front and centre. Tackle them in order.

Avg. last frost April 8
Avg. first frost November 12
Soil temp (4") 79°F
Watering Critical
Pest pressure High
Daylight 14.6 hrs
  1. Pick ageratum

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

July prep starts now
  • 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.

Calaveras County, California is in USDA Zone 9a. The average last spring frost is April 8 and the first fall frost is November 12, giving you a growing season of approximately 218 days.

At an elevation of 2,363 feet, Calaveras County receives approximately 25 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Calaveras County, CA (Zone 9a) Long season
218 days
Last Spring Frost April 8
218 growing days
First Fall Frost November 12

Calaveras County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.6

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (36 days to spare)
Start indoors: Jan 19 Transplant: Feb 16 🌸 Bloom: Apr 13 – Sep 28
Recommended (50%) ✓ Fits season (8 days to spare)
Start indoors: Feb 25 Transplant: Mar 25 🌸 Bloom: May 20 – Nov 4
Safe Start (90%) ✓ Fits season (8 days to spare)
Start indoors: Mar 27 Transplant: Apr 24 🌸 Bloom: Jun 19 – Dec 4

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 Calaveras County

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

Soil pH

Your soil pH (6.5–7.6) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 218-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
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,207 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 5.4" 0" ❄️ Dormant
Feb 4.8" 0" ❄️ Dormant
Mar 4" 0" ❄️ Dormant
Apr 4.3" 2.4" 1.9" 💧 Light watering
May 4.3" 0.7" 3.6" 🚿 Regular watering
Jun 4.3" 0.2" 4.1" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.3" 4" 🚿 Regular watering
Oct 4.3" 1" 3.3" 🚿 Regular watering
Nov 4.3" 2.3" 2" 💧 Light watering
Dec 3.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Calaveras 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 ~827 GDD — county provides 2,670 GDD Excellent fit

Ageratum Planting Timeline — Calaveras County, CA

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 – Mar 11
Transplant Outdoors March 25 Mar 25 – Apr 8
Direct Sow March 25 Mar 25 – Apr 15
Bloom May 20 May 20 – Nov 4

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 9a

📆 Growing Season

218 days in Calaveras County

Growing Tips for Ageratum in Calaveras County

Direct sow Ageratum outdoors after April 08 in Calaveras 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 Calaveras County, CA?

Calaveras County is in Zone 9a with an average last frost of April 8. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Calaveras County, CA?

Calaveras County, California is in USDA Hardiness Zone 9a. The average last spring frost is April 8 and first fall frost is November 12.

When should I plant Ageratum in Calaveras County County, ?

In Calaveras County County, , plant Ageratum after the last frost (around April 8) and before the first frost (around November 12). Best results when soil holds above 50°F.

What growing zone is Calaveras County County, for Ageratum?

Calaveras County County sits in USDA Zone 9a. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Calaveras County County's climate?

Yes — Ageratum grows well in Calaveras County County's temperate climate. Calaveras County County averages a 218-day frost-free season, with last frost around April 8 and first frost around November 12.

🌱

Your Calaveras County Garden Planner — Free

A 22-page printable planner built for Calaveras County (Zone 9a). 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 Calaveras County, CA. 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.