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When to Plant Cosmos in Throckmorton County, TX

Cosmos (Cosmos bipinnatus) is an airy, feathery-foliaged cottage garden annual from Mexico that thrives on neglect. It produces delicate daisy-like blooms in shades of pink, white, and magenta from midsummer until frost. Cosmos is a prolific self-sower — once established in a garden it often returns year after year without replanting. Excellent habitat plant for beneficial insects.

Throckmorton County, Texas is in USDA Zone 8a. The average last spring frost is March 31 and the first fall frost is November 9, giving you a growing season of approximately 223 days.

At an elevation of 4,952 feet, Throckmorton County receives approximately 60.7 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Cosmos during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cosmos root diseases.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Throckmorton County, TX (Zone 8a) Long season
223 days
Last Spring Frost March 31
223 growing days
First Fall Frost November 9

Throckmorton County Soil Profile

Soil Type

Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Cosmos Planting Timeline — Throckmorton County, TX

Cosmos Planting Calendar

Activity When Date Range
Start Indoors March 3 Mar 3 – Mar 17
Transplant Outdoors March 17 Mar 17 – Mar 31
Direct Sow March 17 Mar 17 – Apr 7
Bloom May 26 May 26 – Oct 13

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Low — drought tolerant

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–8 · Your soil: N/A

🗺️ USDA Zone

Zone 8a

📆 Growing Season

223 days in Throckmorton County

Growing Tips for Throckmorton County

Direct-sow after last frost; cosmos germinates readily at 65-80°F in 7-10 days. Avoid rich soil — excess fertility produces lush foliage at the expense of blooms. Cosmos tolerates poor, dry soil exceptionally well. Pinch seedlings at 8 inches to encourage branching. Self-sows freely; allow some seed heads to mature and drop for a no-fuss perennial effect in warm climates.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cosmos in Throckmorton County, TX?

Throckmorton County is in Zone 8a with an average last frost of March 31. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.

What planting zone is Throckmorton County, TX?

Throckmorton County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 31 and first fall frost is November 9.

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Your Throckmorton County Garden Planner — Free

A 22-page printable planner built for Throckmorton 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 Throckmorton 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.