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When to plant Ageratum in Applegate, CA

Applegate sits in USDA Zone 9b. Plant Ageratum between April 1 (after last frost on April 22) and April 22.

When to Plant Ageratum in Applegate, CA

Placer County, California Zone 9b August

Placer County, California gardeners: here's your August plan

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

Avg. last frost April 22
Avg. first frost November 9
Soil temp (4") 89°F
Watering Critical
Pest pressure High
Daylight 13.5 hrs
  1. Collect ageratum at their peak

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

Before September 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.

Applegate, California is in USDA Zone 9b. The average last spring frost is April 22 and the first fall frost is November 9, giving you a growing season of approximately 201 days.

At an elevation of 651 feet, Placer County receives approximately 25.3 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Applegate, CA (Zone 9b) Long season
201 days
Last Spring Frost April 22
201 growing days
First Fall Frost November 9

Applegate Soil Profile

Soil Type

Loam

Soil pH

6.6-7.2

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 3 Transplant: Mar 24 🌸 Bloom: May 19 – Nov 17
Recommended (50%) ✗ May not fit
Start indoors: Mar 11 Transplant: Apr 1 🌸 Bloom: May 27 – Nov 25
Safe Start (90%) ✗ May not fit
Start indoors: Apr 16 Transplant: May 7 🌸 Bloom: Jul 2 – Dec 31

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 Applegate

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

Soil pH

Your soil pH (6.6–7.2) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Ageratum.

Organic Matter

Organic matter is moderate (3.1%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 201-day season

Sow every 6.9 weeks. Last sowing by Aug 26 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,656 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 5.2" 0" ❄️ Dormant
Feb 5.3" 0" ❄️ Dormant
Mar 4.2" 0" ❄️ Dormant
Apr 4.3" 1.7" 2.6" 🚿 Regular watering
May 4.3" 0.7" 3.6" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 1.1" 3.2" 🚿 Regular watering
Nov 4.3" 2.4" 1.9" 💧 Light watering
Dec 4.4" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Placer 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 ~928 GDD — county provides 2,763 GDD Excellent fit

Ageratum Planting Timeline — Applegate, CA

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 11 Mar 11 – Mar 25
Transplant Outdoors April 1 Apr 1 – Apr 15
Direct Sow April 1 Apr 1 – Apr 22
Bloom May 27 May 27 – Nov 25

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
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 · 2-3 times/week

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

201 days in Placer County

Growing Tips for Ageratum in Applegate

Direct sow Ageratum outdoors after April 22 in Placer 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 →

When should I plant Ageratum in Applegate, CA?

In Applegate, CA, plant Ageratum after the last frost (around April 22) and before the first frost (around November 9). Best results when soil holds above 50°F.

What growing zone is Applegate, CA for Ageratum?

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

Can Ageratum grow in Applegate's climate?

Yes — Ageratum grows well in Applegate's temperate climate. Applegate averages a 201-day frost-free season, with last frost around April 22 and first frost around November 9.

🌱

Your Placer County Garden Planner — Free

A 22-page printable planner built for Placer County (Zone 9b). 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 Placer County, CA. Local conditions may vary. Last updated: August 2026.