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When to plant Ageratum in Santa Cruz County County,

For Santa Cruz County County, gardeners: plant Ageratum January 21 through February 11 once soil reads 50°F.

When to Plant Ageratum in Santa Cruz County, CA

Santa Cruz County, California Zone 9b June

June in the garden — Santa Cruz County, California

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

Avg. last frost February 11
Avg. first frost December 4
Soil temp (4") 85°F
Watering Critical
Pest pressure High
Daylight 14.5 hrs
  1. Start harvesting ageratum

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

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.

Santa Cruz County, California is in USDA Zone 9b. The average last spring frost is February 11 and the first fall frost is December 4, giving you a growing season of approximately 296 days.

At an elevation of 353 feet, Santa Cruz County receives approximately 18.3 inches of rainfall annually with predominantly loam soil. Summer highs average 94°F, providing good warmth for Ageratum during the growing season. With low rainfall, drip irrigation is essential for growing Ageratum successfully. Mulch heavily to conserve soil moisture.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Santa Cruz County, CA (Zone 9b) Year-round
296 days
Last Spring Frost February 11
296 growing days
First Fall Frost December 4

Santa Cruz County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (87 days to spare)
Start indoors: Dec 17 Transplant: Jan 7 🌸 Bloom: Mar 4 – Sep 2
Recommended (50%) ✓ Fits season (79 days to spare)
Start indoors: Dec 31 Transplant: Jan 21 🌸 Bloom: Mar 18 – Sep 16
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Feb 3 Transplant: Feb 24 🌸 Bloom: Apr 21 – Oct 20

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 Santa Cruz County

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

Soil pH

Your soil pH (6.4–7.7) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

5
successive plantings in your 296-day season

Sow every 6.9 weeks. Last sowing by Sep 20 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,351 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 3.6" 0" ❄️ Dormant
Feb 4.3" 4.2" 0.1" 💧 Light watering
Mar 4.3" 2.8" 1.5" 💧 Light watering
Apr 4.3" 1.5" 2.8" 🚿 Regular watering
May 4.3" 0.5" 3.8" 🚿 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" 0.7" 3.6" 🚿 Regular watering
Nov 4.3" 1.6" 2.7" 🚿 Regular watering
Dec 4.3" 3" 1.3" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Santa Cruz 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 ~1,384 GDD — county provides 6,088 GDD Excellent fit

Ageratum Planting Timeline — Santa Cruz County, CA

Ageratum Planting Calendar

Activity When Date Range
Start Indoors December 31 Dec 31 – Jan 14
Transplant Outdoors January 21 Jan 21 – Feb 4
Direct Sow January 21 Jan 21 – Feb 11
Bloom March 18 Mar 18 – Sep 16

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

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: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

296 days in Santa Cruz County

Growing Tips for Ageratum in Santa Cruz County

Direct sow Ageratum outdoors after February 11 in Santa Cruz 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.

Santa Cruz County receives only 18" of rain annually. Ageratum needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Santa Cruz County, CA?

Santa Cruz County is in Zone 9b with an average last frost of February 11. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Santa Cruz County, CA?

Santa Cruz County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 11 and first fall frost is December 4.

When should I plant Ageratum in Santa Cruz County County, ?

In Santa Cruz County County, , plant Ageratum after the last frost (around February 11) and before the first frost (around December 4). Best results when soil holds above 50°F.

What growing zone is Santa Cruz County County, for Ageratum?

Santa Cruz 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 Santa Cruz County County's climate?

Yes — Ageratum grows well in Santa Cruz County County's temperate climate. Santa Cruz County County averages a 297-day frost-free season, with last frost around February 11 and first frost around December 4.

🌱

Your Santa Cruz County Garden Planner — Free

A 22-page printable planner built for Santa Cruz 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 Santa Cruz 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.