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When to plant Foxglove in Hamilton County County,

Hamilton County County's spring Foxglove window runs May 15 through June 5. time plantings around the expected last-frost window for best survival.

When to Plant Foxglove in Hamilton County, IA

Hamilton County, Iowa Zone 5a June

Your June planting checklist for Hamilton County, Iowa

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Hamilton County, Iowa.

Avg. last frost May 1
Avg. first frost October 7
Soil temp (4") 63°F
Watering Low
Pest pressure High
Daylight 15.1 hrs
July prep starts now
  • Starting indoors: foxglove
  • First harvests: foxglove

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Foxglove (Digitalis purpurea) is a stately cottage garden classic, sending up dramatic 3–5 foot spires of tubular flowers — spotted purple, pink, white, or cream — in late spring and early summer. Technically biennial (flowering in its second year), foxglove perpetuates itself so freely from self-sown seed that established plantings appear to be permanent perennials. A key source plant for the heart medication digitalis, all parts are highly toxic if ingested. Bumblebees are the primary pollinators, crawling deep into each bell-shaped flower. Partial shade and cool, moist woodland-edge conditions suit foxglove best; it resents heat and drought.

Hamilton County, Iowa is in USDA Zone 5a. The average last spring frost is May 1 and the first fall frost is October 7, giving you a growing season of approximately 159 days.

At an elevation of 1,210 feet, Hamilton County receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Foxglove to ensure they mature before fall.

Perennial Blooms in Spring Pollinator-friendly Deer-resistant Good for cutting
Hamilton County, IA (Zone 5a) Moderate season
159 days
Last Spring Frost May 1
159 growing days
First Fall Frost October 7
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Hamilton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.8

Drainage

Well Drained

Foxglove Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Start indoors: Feb 20 Transplant: May 8 🌸 Bloom: Jul 3 – Aug 14
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Feb 27 Transplant: May 15 🌸 Bloom: Jul 10 – Aug 21
Safe Start (90%) ✓ Fits season (43 days to spare)
Start indoors: Mar 12 Transplant: May 28 🌸 Bloom: Jul 23 – Sep 3

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 Hamilton County

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

Soil pH

Your soil pH (5.8–6.8) overlaps with Foxglove's range (5.5–6.5), though not a perfect match.

Soil Texture

The silt loam soil in Hamilton County is excellent for Foxglove — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Foxglove.

How to Plant Foxglove

0.1"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Foxglove

2
successive plantings in your 159-day season

Sow every 9.1 weeks. Last sowing by Jun 09 to harvest before frost.

Foxglove Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 92 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Foxglove

Foxglove needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Foxglove Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Hamilton County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Foxglove 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.

Foxglove needs ~1,000 GDD — county provides 1,590 GDD Excellent fit

Foxglove Planting Timeline — Hamilton County, IA

Foxglove Planting Calendar

Activity When Date Range
Start Indoors February 27 Feb 27 – Mar 13
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 15 May 15 – Jun 5
Bloom July 10 Jul 10 – Aug 21

Plant 0.1" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

159 days in Hamilton County

Growing Tips for Foxglove in Hamilton County

Direct sow Foxglove outdoors after May 01 in Hamilton County when soil has warmed and frost danger has passed.

General growing tips

Sow seeds indoors 8–10 weeks before last frost or direct-sow outdoors in late spring/early summer for next-year bloom (biennial cycle). Surface-sow — seeds need light to germinate. Transplant after last frost into cool, moist, well-amended soil. Morning sun with afternoon shade is ideal; full shade reduces bloom but is tolerated. Keep consistently moist. First-year plants form a basal rosette only; second-year plants produce flower spikes. After bloom, cut the main spike before seed scatters to prevent excessive spreading, or leave some spikes to self-seed for naturalizing. Perennial species (D. grandiflora, D. x mertonensis) maintain clumps without requiring self-seeding. Wear gloves when handling — all plant parts toxic.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Foxglove in Hamilton County, IA?

Hamilton County is in Zone 5a with an average last frost of May 1. Plan your Foxglove planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hamilton County, IA?

Hamilton County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 1 and first fall frost is October 7.

When should I plant Foxglove in Hamilton County County, ?

In Hamilton County County, , plant Foxglove after the last frost (around May 1) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Hamilton County County, for Foxglove?

Hamilton County County sits in USDA Zone 5a. Foxglove grows reliably in zones 3a through 9a, so it's a good fit here.

Can Foxglove grow in Hamilton County County's climate?

Yes — Foxglove grows well in Hamilton County County's temperate climate. Hamilton County County averages a 159-day frost-free season, with last frost around May 1 and first frost around October 7.

🌱

Your Hamilton County Garden Planner — Free

A 22-page printable planner built for Hamilton County (Zone 5a). 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 Hamilton County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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