When to plant Ageratum in Harrison County County,
Harrison County County gardeners should plant Ageratum between May 1 and May 22 in spring. With Harrison County County's Zone 5b climate (last frost April 24), Ageratum needs 75 days to mature — plant by July 27 for a full harvest.
When to Plant Ageratum in Harrison County, IA
Your June planting checklist for Harrison County, Iowa
Here's what deserves your attention in Harrison County, Iowa this month. Everything below is tailored to Zone 5b and timed around your local frost dates.
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Time to start ageratum inside
These need a head start before your last frost (April 24). Sow into cells now so you're ready to transplant in a few weeks.
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Harvest ageratum as they ripen
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
July will be here before you know it — start on
- First harvests: ageratum
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.
Harrison County, Iowa is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 10, giving you a growing season of approximately 169 days.
At an elevation of 1,345 feet, Harrison County receives approximately 35.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Ageratum to ensure they mature before fall.
Harrison County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.2
Drainage
Well Drained
Ageratum Planting Risk Windows
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 Harrison County
How your county's soil matches Ageratum's growing requirements.
Soil pH
Your soil pH (5.8–7.2) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Harrison County is excellent for Ageratum — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Ageratum will thrive.
How to Plant Ageratum
Succession Planting Ageratum
Sow every 6.9 weeks. Last sowing by Jul 27 to harvest before frost.
Ageratum Water Budget
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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| May | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jun | 4.3" | 5.2" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Aug | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Harrison 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 Planting Timeline — Harrison County, IA
Ageratum Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 6 | Mar 6 – Mar 20 |
| Transplant Outdoors | May 1 | May 1 – May 15 |
| Direct Sow | May 1 | May 1 – May 22 |
| Bloom | June 26 | Jun 26 – Sep 25 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| 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: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
169 days in Harrison County
Growing Tips for Ageratum in Harrison County
Direct sow Ageratum outdoors after April 24 in Harrison 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 →
Ageratum in Other Locations
Frequently Asked Questions
When should I plant Ageratum in Harrison County, IA?
Harrison County is in Zone 5b with an average last frost of April 24. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harrison County, IA?
Harrison County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 10.
When should I plant Ageratum in Harrison County, ?
In Harrison County, , plant Ageratum after the last frost (around April 24) and before the first frost (around October 10). Best results when soil holds above 50°F.
What growing zone is Harrison County, for Ageratum?
Harrison 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 Harrison County's climate?
Yes — Ageratum grows well in Harrison County's temperate climate. Harrison County averages a 169-day frost-free season, with last frost around April 24 and first frost around October 10.
Your Harrison County Garden Planner — Free
A 22-page printable planner built for Harrison 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.