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When to plant Ageratum in Archuleta County County,

Plant Ageratum in Archuleta County County during the brief June 20–July 11 window. With 96 frost-free days, fall plantings can't mature before September 17.

When to Plant Ageratum in Archuleta County, CO

Archuleta County, Colorado Zone 5b June

Archuleta County, Colorado gardeners: here's your June plan

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

Avg. last frost June 13
Avg. first frost September 17
Soil temp (4") 56°F
Watering Critical
Pest pressure High
Daylight 14.5 hrs
  1. Get ageratum in the ground

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Sow ageratum where they'll grow

    These tolerate cool soil, so you're not gambling by sowing now.

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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.

Archuleta County, Colorado is in USDA Zone 5b. The average last spring frost is June 13 and the first fall frost is September 17, giving you a growing season of approximately 96 days.

At an elevation of 5,346 feet, Archuleta County receives approximately 14 inches of rainfall annually with predominantly loam soil. Summer highs average 85°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
Archuleta County, CO (Zone 5b) Very short season
96 days
Last Spring Frost June 13
96 growing days
First Fall Frost September 17
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Archuleta County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 18 Transplant: Jun 13 🌸 Bloom: Aug 8 – Nov 7
Recommended (50%) ✗ May not fit
Start indoors: Apr 25 Transplant: Jun 20 🌸 Bloom: Aug 15 – Nov 14
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jul 1 🌸 Bloom: Aug 26 – Nov 25

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 Archuleta County

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

Soil pH

Your soil pH (6.3–7.9) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 397 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 0.9" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 1.9" 0" ❄️ Dormant
Jun 4.3" 1.1" 3.2" 🚿 Regular watering
Jul 4.3" 1.3" 3" 🚿 Regular watering
Aug 4.3" 1.3" 3" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Archuleta 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 1,320 GDD Excellent fit

Ageratum Planting Timeline — Archuleta County, CO

Ageratum Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 20 Jun 20 – Jul 4
Direct Sow June 20 Jun 20 – Jul 11
Bloom August 15 Aug 15 – Nov 14

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
August Bloom
September Bloom
October Bloom
November Bloom
December
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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 5b

📆 Growing Season

96 days in Archuleta County

Growing Tips for Ageratum in Archuleta County

Direct sow Ageratum outdoors after June 13 in Archuleta 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.

Archuleta County receives only 14" 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 Archuleta County, CO?

Archuleta County is in Zone 5b with an average last frost of June 13. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Archuleta County, CO?

Archuleta County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 13 and first fall frost is September 17.

When should I plant Ageratum in Archuleta County, ?

In Archuleta County, , plant Ageratum after the last frost (around June 13) and before the first frost (around September 17). Best results when soil holds above 50°F.

What growing zone is Archuleta County, for Ageratum?

Archuleta County sits in USDA Zone 5b. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Archuleta County's climate?

Yes — Ageratum grows well in Archuleta County's temperate climate. Archuleta County averages a 96-day frost-free season, with last frost around June 13 and first frost around September 17.

🌱

Your Archuleta County Garden Planner — Free

A 22-page printable planner built for Archuleta County (Zone 5b). 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 Archuleta County, CO. 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.