When to Plant Cosmos in Lamb 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.
Lamb County, Texas is in USDA Zone 7a. The average last spring frost is April 8 and the first fall frost is October 27, giving you a growing season of approximately 202 days.
At an elevation of 1,440 feet, Lamb County receives approximately 56.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°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.
Lamb County Soil Profile
Soil Type
Sandy Loam
Soil pH
7.5-8.4
Drainage
Well Drained
Monthly Watering Guide for Cosmos
Cosmos needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Cosmos Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.9" | 0" | ❄️ Dormant |
| Feb | — | 2.8" | 0" | ❄️ Dormant |
| Mar | — | 3.5" | 0" | ❄️ Dormant |
| Apr | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| May | 4.3" | 1.2" | 3.1" | 🚿 Regular watering |
| Jun | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Jul | 4.3" | 8.9" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 11.2" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 8.8" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 5.2" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.4" | 0" | ❄️ Dormant |
| Dec | — | 3.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Lamb County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Cosmos Planting Timeline — Lamb County, TX
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | April 8 | Apr 8 – Apr 22 |
| Direct Sow | April 8 | Apr 8 – Apr 29 |
| Bloom | June 17 | Jun 17 – Oct 7 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| 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 7a
📆 Growing Season
202 days in Lamb County
Growing Tips for Lamb 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 →
Cosmos in Other Locations
Frequently Asked Questions
When should I plant Cosmos in Lamb County, TX?
Lamb County is in Zone 7a with an average last frost of April 8. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lamb County, TX?
Lamb County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 8 and first fall frost is October 27.
Your Lamb County Garden Planner — Free
A 22-page printable planner built for Lamb County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.