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When to plant Ageratum in Tuolumne County County,

Tuolumne County County's spring Ageratum window runs April 4 through April 25. aim for a steady week of warm soil before planting.

When to Plant Ageratum in Tuolumne County, CA

Tuolumne County, California Zone 9b June

Your June planting checklist for Tuolumne County, California

Your garden in Tuolumne County, California is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost April 25
Avg. first frost October 27
Soil temp (4") 70°F
Watering Critical
Pest pressure High
Daylight 14.6 hrs
  1. Fire up the seed-starting tray: ageratum

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

  2. Basket week: ageratum

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

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.

Tuolumne County, California is in USDA Zone 9b. The average last spring frost is April 25 and the first fall frost is October 27, giving you a growing season of approximately 185 days.

At an elevation of 2,990 feet, Tuolumne County receives approximately 37.7 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Tuolumne County, CA (Zone 9b) Moderate season
185 days
Last Spring Frost April 25
185 growing days
First Fall Frost October 27

Tuolumne County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.5

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 14 Transplant: Apr 4 🌸 Bloom: May 30 – Nov 28
Safe Start (90%) ✓ Fits season (298 days to spare)
Start indoors: May 9 Transplant: May 30 🌸 Bloom: Jul 25 – Jan 23

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 Tuolumne County

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

Soil pH

Your soil pH (6.6–7.5) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Tuolumne 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

3
successive plantings in your 185-day season

Sow every 6.9 weeks. Last sowing by Aug 13 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 285 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 7.8" 0" ❄️ Dormant
Feb 8.2" 0" ❄️ Dormant
Mar 6.7" 0" ❄️ Dormant
Apr 4.3" 2.8" 1.5" 💧 Light watering
May 4.3" 1.1" 3.2" 🚿 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" 0.4" 3.9" 🚿 Regular watering
Oct 4.3" 1.5" 2.8" 🚿 Regular watering
Nov 3" 0" ❄️ Dormant
Dec 6.1" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Tuolumne 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 ~1,080 GDD — county provides 2,960 GDD Excellent fit

Ageratum Planting Timeline — Tuolumne County, CA

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors April 4 Apr 4 – Apr 18
Direct Sow April 4 Apr 4 – Apr 25
Bloom May 30 May 30 – Nov 28

· 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 · Only during dry spells

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

185 days in Tuolumne County

Growing Tips for Ageratum in Tuolumne County

Direct sow Ageratum outdoors after April 25 in Tuolumne 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 Tuolumne County, CA?

Tuolumne County is in Zone 9b with an average last frost of April 25. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Tuolumne County, CA?

Tuolumne County, California is in USDA Hardiness Zone 9b. The average last spring frost is April 25 and first fall frost is October 27.

When should I plant Ageratum in Tuolumne County County, ?

In Tuolumne County County, , plant Ageratum after the last frost (around April 25) and before the first frost (around October 27). Best results when soil holds above 50°F.

What growing zone is Tuolumne County County, for Ageratum?

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

Can Ageratum grow in Tuolumne County County's climate?

Yes — Ageratum grows well in Tuolumne County County's temperate climate. Tuolumne County County averages a 185-day frost-free season, with last frost around April 25 and first frost around October 27.

🌱

Your Tuolumne County Garden Planner — Free

A 22-page printable planner built for Tuolumne 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 Tuolumne 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.