When to Plant Cosmos in Tom Green County, TX
What to do in June
Welcome to June in Zone 8a. These are the moves that will have the biggest impact on your growing season.
-
Harvest cosmos as they ripen
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
Coming up in July — start thinking about
- First harvests: cosmos
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.
Tom Green County, Texas is in USDA Zone 8a. The average last spring frost is March 25 and the first fall frost is November 12, giving you a growing season of approximately 232 days.
At an elevation of 4,366 feet, Tom Green County receives approximately 52.3 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 102°F, so Cosmos may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Cosmos will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cosmos root diseases.
Tom Green County Soil Profile
Soil Type
Sandy Loam
Soil pH
7.2-8.3
Drainage
Well Drained
Cosmos Planting Risk Windows
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 Tom Green County
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (7.2–8.3) overlaps with Cosmos's range (6.0–8.0), though not a perfect match.
Soil Texture
Sandy soil in Tom Green County warms quickly in spring but drains fast. Cosmos will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Cosmos.
Organic Matter
Organic matter is low (0.9%). Add 2-3 inches of compost before planting Cosmos.
How to Plant Cosmos
Succession Planting Cosmos
Sow every 6.9 weeks. Last sowing by Aug 14 to harvest before frost.
Cosmos Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Cosmos
Cosmos 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 | Cosmos Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3" | 0" | ❄️ Dormant |
| Feb | — | 3.1" | 0" | ❄️ Dormant |
| Mar | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| May | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Jun | 2.2" | 1.9" | 0.3" | 💧 Light watering |
| Jul | 2.2" | 9.5" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 10.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 7.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 4.8" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Tom Green County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Cosmos 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.
Cosmos Planting Timeline — Tom Green County, TX
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | March 11 | Mar 11 – Mar 25 |
| Direct Sow | March 11 | Mar 11 – Apr 1 |
| Bloom | May 20 | May 20 – Oct 7 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| 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
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
232 days in Tom Green County
Growing Tips for Cosmos in Tom Green County
Direct sow Cosmos outdoors after March 25 in Tom Green County when soil has warmed and frost danger has passed.
Sandy soil in Tom Green County dries quickly — mulch Cosmos with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 102°F in Tom Green County, provide afternoon shade for Cosmos and water deeply in the morning.
Common pests for Cosmos 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; 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 →
Cosmos in Other Locations
Frequently Asked Questions
When should I plant Cosmos in Tom Green County, TX?
Tom Green County is in Zone 8a with an average last frost of March 25. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Tom Green County, TX?
Tom Green County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 25 and first fall frost is November 12.
Your Tom Green County Garden Planner — Free
A 22-page printable planner built for Tom Green 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.