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When to Plant Impatiens in Knox County, TX

Knox County, Texas Zone 8a June

This month in Knox County, Texas

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

Avg. last frost March 24
Avg. first frost November 12
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 14.2 hrs
  1. Start harvesting impatiens

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

July prep starts now
  • 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.

Knox County, Texas is in USDA Zone 8a. The average last spring frost is March 24 and the first fall frost is November 12, giving you a growing season of approximately 233 days.

At an elevation of 1,847 feet, Knox County receives approximately 51.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Impatiens during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Impatiens root diseases.

Annual Blooms in Summer Pollinator-friendly
Knox County, TX (Zone 8a) Long season
233 days
Last Spring Frost March 24
233 growing days
First Fall Frost November 12

Knox County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.2

Drainage

Well Drained

Impatiens Planting Risk Windows

Early Start (70% safe) ✓ Fits season (20 days to spare)
Start indoors: Jan 20 Transplant: Mar 17 🌸 Bloom: May 26 – Oct 13
Recommended (50%) ✓ Fits season (23 days to spare)
Start indoors: Jan 27 Transplant: Mar 24 🌸 Bloom: Jun 2 – Oct 20
Safe Start (90%) ✓ Fits season (16 days to spare)
Start indoors: Feb 16 Transplant: Apr 13 🌸 Bloom: Jun 22 – Nov 9

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 Knox County

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

Soil pH

Your soil pH (6.4–7.2) is more alkaline than Impatiens prefers (6.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is low (1.9%). Add 2-3 inches of compost before planting Impatiens.

How to Plant Impatiens

10"
Between Plants
12"
Between Rows

Succession Planting Impatiens

4
successive plantings in your 233-day season

Sow every 6.9 weeks. Last sowing by Aug 29 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 160 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 1.3" 0" ❄️ Dormant
Feb 2.1" 0" ❄️ Dormant
Mar 4.3" 3.2" 1.1" 💧 Light watering
Apr 4.3" 6.4" 0" ✅ Rainfall sufficient
May 4.3" 6.7" 0" ✅ Rainfall sufficient
Jun 4.3" 7.3" 0" ✅ Rainfall sufficient
Jul 4.3" 6.5" 0" ✅ Rainfall sufficient
Aug 4.3" 5.9" 0" ✅ Rainfall sufficient
Sep 4.3" 5.4" 0" ✅ Rainfall sufficient
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 4.3" 1.8" 2.5" 🚿 Regular watering
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Knox 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 ~1,333 GDD — county provides 4,601 GDD Excellent fit

Impatiens Planting Timeline — Knox County, TX

Impatiens Planting Calendar

Activity When Date Range
Start Indoors January 27 Jan 27 – Feb 10
Transplant Outdoors March 24 Mar 24 – Apr 7
Bloom June 2 Jun 2 – Oct 20

· 10" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Start Indoors
March Transplant Outdoors
April Transplant Outdoors
May
June Bloom
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: too_alkaline

🗺️ USDA Zone

Zone 8a

📆 Growing Season

233 days in Knox County

Growing Tips for Impatiens in Knox County

Direct sow Impatiens outdoors after March 24 in Knox 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 Knox County, TX?

Knox County is in Zone 8a with an average last frost of March 24. Plan your Impatiens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Knox County, TX?

Knox County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 24 and first fall frost is November 12.

🌱

Your Knox County Garden Planner — Free

A 22-page printable planner built for Knox County (Zone 8a). 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 Knox County, TX. 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.