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When to plant Impatiens in Delaware County, IA

In Delaware County, Impatiens is a spring-only crop. Plant May 9–May 23 once soil hits 50°F.

When to Plant Impatiens in Delaware County, IA

Delaware County, Iowa Zone 5a July

July to-do list for Delaware County, Iowa

If you only do a handful of things in the garden this July, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 2
Avg. first frost October 7
Soil temp (4") 75°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Collect impatiens at their peak

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

August will be here before you know it — start on
  • First harvests: impatiens

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Impatiens (Impatiens walleriana) are the go-to annual for shaded beds and containers. They produce a continuous carpet of flat-faced blooms from transplant until frost, needing little deadheading. Their preference for consistent moisture and part-shade makes them ideal under trees and along north-facing borders.

Delaware County, Iowa is in USDA Zone 5a. The average last spring frost is May 2 and the first fall frost is October 7, giving you a growing season of approximately 158 days.

At an elevation of 974 feet, Delaware County receives approximately 31.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Impatiens to ensure they mature before fall.

Annual Blooms in Summer Pollinator-friendly
Delaware County, IA (Zone 5a) Moderate season
158 days
Last Spring Frost May 2
158 growing days
First Fall Frost October 7

Delaware County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.8

Drainage

Well Drained

Impatiens Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 28 Transplant: May 2 🌸 Bloom: Jul 11 – Oct 3
Recommended (50%) ✗ May not fit
Start indoors: Mar 7 Transplant: May 9 🌸 Bloom: Jul 18 – Oct 10
Safe Start (90%) ✗ May not fit
Start indoors: Mar 21 Transplant: May 23 🌸 Bloom: Aug 1 – Oct 24

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 Delaware County

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

Soil pH

Your soil pH (6.0–6.8) overlaps with Impatiens's range (6.0–6.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Impatiens will thrive.

How to Plant Impatiens

10"
Between Plants
12"
Between Rows

Succession Planting Impatiens

3
successive plantings in your 158-day season

Sow every 6.9 weeks. Last sowing by Jul 24 to harvest before frost.

Impatiens Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 236 gal / 100 sq ft

Monthly Watering Guide for Impatiens

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

Month Impatiens Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 4.3" 3.2" 1.1" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.6" 1.7" 💧 Light watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 1.8" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

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

Impatiens 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.

Impatiens needs ~827 GDD — county provides 1,935 GDD Excellent fit

Impatiens Planting Timeline — Delaware County, IA

Impatiens Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors May 9 May 9 – May 23
Bloom July 18 Jul 18 – Oct 10

· 10" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

158 days in Delaware County

Growing Tips for Impatiens in Delaware County

Direct sow Impatiens outdoors after May 02 in Delaware County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors 8–10 weeks before last frost at 70–75°F; germination requires light — do not cover seeds. Transplant after last frost once nights consistently exceed 50°F. Water regularly — wilting causes bud drop and they rarely fully recover the same flush. Watch for impatiens downy mildew (IDM); consider New Guinea impatiens as a resistant alternative in affected regions. Pinch tips at planting to encourage branching.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Impatiens in Delaware County, IA?

Delaware County is in Zone 5a with an average last frost of May 2. Plan your Impatiens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Delaware County, IA?

Delaware County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 2 and first fall frost is October 7.

When should I plant Impatiens in Delaware County, IA?

In Delaware County, IA, plant Impatiens after the last frost (around May 2) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Delaware County, IA for Impatiens?

Delaware County sits in USDA Zone 5a. Impatiens grows reliably in zones 2a through 11b, so it's a good fit here.

Can Impatiens grow in Delaware County's climate?

Yes — Impatiens grows well in Delaware County's temperate climate. Delaware County averages a 158-day frost-free season, with last frost around May 2 and first frost around October 7.

🌱

Your Delaware County Garden Planner — Free

A 22-page printable planner built for Delaware 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 Delaware County, IA. Local conditions may vary. Last updated: July 2026.

Sources & credits

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