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When to Plant Zinnia in San Augustine County, TX

San Augustine County, Texas Zone 9a June

June in San Augustine County, Texas — your action list

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

Avg. last frost March 5
Avg. first frost November 16
Soil temp (4") 84°F
Watering Low
Pest pressure High
Daylight 14 hrs
  1. Harvest zinnia as they ripen

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Coming up in July — start thinking about
  • First harvests: zinnia

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Zinnia (Zinnia elegans) is a fast-growing, heat-loving annual that produces bold, dahlia-like blooms from early summer until hard frost. One of the easiest flowers to grow from direct-sown seed, zinnias thrive in hot, dry conditions and are magnets for butterflies and beneficial insects. They make excellent companion plants alongside marigolds in the vegetable garden.

San Augustine County, Texas is in USDA Zone 9a. The average last spring frost is March 5 and the first fall frost is November 16, giving you a growing season of approximately 256 days.

At an elevation of 146 feet, San Augustine County receives approximately 62.7 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Zinnia may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Zinnia will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Zinnia root diseases.

Annual Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
San Augustine County, TX (Zone 9a) Long season
256 days
Last Spring Frost March 5
256 growing days
First Fall Frost November 16

San Augustine County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.4-6.6

Drainage

Well Drained

Zinnia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Jan 28 Transplant: Feb 4 🌸 Bloom: Apr 15 – Sep 30
Recommended (50%) ✓ Fits season (39 days to spare)
Start indoors: Feb 5 Transplant: Feb 12 🌸 Bloom: Apr 23 – Oct 8
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Mar 4 Transplant: Mar 11 🌸 Bloom: May 20 – Nov 4

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 San Augustine County

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

Soil pH

Your soil pH (5.4–6.6) overlaps with Zinnia's range (5.5–7.5), though not a perfect match.

Soil Texture

Sandy soil in San Augustine County warms quickly in spring but drains fast. Zinnia will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is low (1.8%). Add 2-3 inches of compost before planting Zinnia.

How to Plant Zinnia

0.3"
Planting Depth
12"
Between Plants
18"
Between Rows

Succession Planting Zinnia

5
successive plantings in your 256-day season

Sow every 6.9 weeks. Last sowing by Sep 07 to harvest before frost.

Zinnia Water Budget

Plant needs
0.5″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Zinnia

Zinnia needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Zinnia Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.2" 3.6" 0" ✅ Rainfall sufficient
Apr 2.2" 6.2" 0" ✅ Rainfall sufficient
May 2.2" 8.2" 0" ✅ Rainfall sufficient
Jun 2.2" 10.7" 0" ✅ Rainfall sufficient
Jul 2.2" 8.7" 0" ✅ Rainfall sufficient
Aug 2.2" 8.2" 0" ✅ Rainfall sufficient
Sep 2.2" 5.8" 0" ✅ Rainfall sufficient
Oct 2.2" 4.2" 0" ✅ Rainfall sufficient
Nov 2.2" 2.3" 0" ✅ Rainfall sufficient
Dec 1.5" 0" ❄️ Dormant

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

Zinnia 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.

Zinnia needs ~1,430 GDD — county provides 5,632 GDD Excellent fit

Zinnia Planting Timeline — San Augustine County, TX

Zinnia Planting Calendar

Activity When Date Range
Start Indoors February 5 Feb 5 – Feb 19
Transplant Outdoors February 12 Feb 12 – Feb 26
Direct Sow February 12 Feb 12 – Mar 5
Bloom April 23 Apr 23 – Oct 8

Plant 0.3" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

256 days in San Augustine County

Growing Tips for Zinnia in San Augustine County

Direct sow Zinnia outdoors after March 05 in San Augustine County when soil has warmed and frost danger has passed.

Sandy soil in San Augustine County dries quickly — mulch Zinnia with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 96°F in San Augustine County, provide afternoon shade for Zinnia and water deeply in the morning.

Common pests for Zinnia in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct-sow after last frost when soil reaches 60°F; seeds germinate in 5-7 days. In zones 3-5 a brief indoor start (4 weeks) is worthwhile but transplant carefully — zinnias dislike root disturbance. Deadhead frequently to extend bloom. Excellent cut flower; harvesting regularly encourages branching. Avoid overhead watering to reduce powdery mildew.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zinnia in San Augustine County, TX?

San Augustine County is in Zone 9a with an average last frost of March 5. Plan your Zinnia planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Augustine County, TX?

San Augustine County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 5 and first fall frost is November 16.

🌱

Your San Augustine County Garden Planner — Free

A 22-page printable planner built for San Augustine County (Zone 9a). 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 San Augustine 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.