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When to plant Impatiens in Kendall County, IL

Plant Impatiens in Kendall County, between April 27 and May 11 — the only viable window. Zone 5b's short season (180 frost-free days) rules out a fall crop.

When to Plant Impatiens in Kendall County, IL

Kendall County, Illinois Zone 5b June

June to-do list for Kendall County, Illinois

A quick June briefing for Kendall County, Illinois gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 20
Avg. first frost October 17
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 15 hrs
  1. Fire up the seed-starting tray: impatiens

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

Looking ahead to July
  • 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.

Kendall County, Illinois is in USDA Zone 5b. The average last spring frost is April 20 and the first fall frost is October 17, giving you a growing season of approximately 180 days.

At an elevation of 708 feet, Kendall County receives approximately 38.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Impatiens during the growing season.

Annual Blooms in Summer Pollinator-friendly
Kendall County, IL (Zone 5b) Moderate season
180 days
Last Spring Frost April 20
180 growing days
First Fall Frost October 17

Kendall County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Impatiens Planting Risk Windows

Early Start (70% safe) ✓ Fits season (14 days to spare)
Start indoors: Feb 17 Transplant: Apr 21 🌸 Bloom: Jun 30 – Sep 29
Recommended (50%) ✓ Fits season (12 days to spare)
Start indoors: Feb 23 Transplant: Apr 27 🌸 Bloom: Jul 6 – Oct 5
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Mar 14 Transplant: May 16 🌸 Bloom: Jul 25 – 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 Kendall County

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

Soil pH

Your soil pH (6.1–6.8) overlaps with Impatiens's range (6.0–6.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.9%) — Impatiens will thrive.

How to Plant Impatiens

10"
Between Plants
12"
Between Rows

Succession Planting Impatiens

3
successive plantings in your 180-day season

Sow every 6.9 weeks. Last sowing by Aug 03 to harvest before frost.

Impatiens Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 174 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 1.7" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 5.3" 0" ✅ Rainfall sufficient
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Kendall 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 ~928 GDD — county provides 2,475 GDD Excellent fit

Impatiens Planting Timeline — Kendall County, IL

Impatiens Planting Calendar

Activity When Date Range
Start Indoors February 23 Feb 23 – Mar 9
Transplant Outdoors April 27 Apr 27 – May 11
Bloom July 6 Jul 6 – Oct 5

· 10" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors
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 5b

📆 Growing Season

180 days in Kendall County

Growing Tips for Impatiens in Kendall County

Direct sow Impatiens outdoors after April 20 in Kendall 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 Kendall County, IL?

Kendall County is in Zone 5b with an average last frost of April 20. Plan your Impatiens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kendall County, IL?

Kendall County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 20 and first fall frost is October 17.

When should I plant Impatiens in Kendall County, IL?

In Kendall County, IL, plant Impatiens after the last frost (around April 20) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Kendall County, IL for Impatiens?

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

Can Impatiens grow in Kendall County's climate?

Yes — Impatiens grows well in Kendall County's temperate climate. Kendall County averages a 180-day frost-free season, with last frost around April 20 and first frost around October 17.

🌱

Your Kendall County Garden Planner — Free

A 22-page printable planner built for Kendall 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 Kendall County, IL. 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.