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When to Plant Cosmos in Lynn County, TX

Lynn County, Texas Zone 8a June

June to-do list for Lynn County, Texas

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost March 31
Avg. first frost November 9
Soil temp (4") 73°F
Watering High
Pest pressure High
Daylight 14.2 hrs
  1. Collect cosmos at their peak

    If you can't use it all right away, check the food-preservation section of your planner.

Before July arrives, get these ready
  • First harvests: cosmos

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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.

Lynn 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 2,252 feet, Lynn County receives approximately 47.6 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 94°F, providing good warmth for Cosmos during the growing season. Sandy soil warms quickly in spring — great for early planting — but Cosmos will need more frequent watering and organic matter to retain nutrients.

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

Lynn County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.5-8.5

Drainage

Well Drained

Cosmos Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Feb 25 Transplant: Mar 11 🌸 Bloom: May 20 – Oct 7
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Mar 3 Transplant: Mar 17 🌸 Bloom: May 26 – Oct 13
Safe Start (90%) ✓ Fits season (26 days to spare)
Start indoors: Mar 18 Transplant: Apr 1 🌸 Bloom: Jun 10 – Oct 28

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 Lynn County

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

Soil pH

Your soil pH (7.5–8.5) overlaps with Cosmos's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is low (1.1%). Add 2-3 inches of compost before planting Cosmos.

How to Plant Cosmos

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

Succession Planting Cosmos

4
successive plantings in your 223-day season

Sow every 6.9 weeks. Last sowing by Aug 11 to harvest before frost.

Cosmos Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/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 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 3.4" 0" ❄️ Dormant
Feb 3.1" 0" ❄️ Dormant
Mar 2.2" 2.8" 0" ✅ Rainfall sufficient
Apr 2.2" 1.8" 0.4" 💧 Light watering
May 2.2" 1" 1.2" 🚿 Regular watering
Jun 2.2" 1.6" 0.6" 💧 Light watering
Jul 2.2" 7.4" 0" ✅ Rainfall sufficient
Aug 2.2" 9.4" 0" ✅ Rainfall sufficient
Sep 2.2" 6.5" 0" ✅ Rainfall sufficient
Oct 2.2" 4.2" 0" ✅ Rainfall sufficient
Nov 2.2" 3.2" 0" ✅ Rainfall sufficient
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Lynn 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 needs ~1,538 GDD — county provides 4,571 GDD Excellent fit

Cosmos Planting Timeline — Lynn 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

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

223 days in Lynn County

Growing Tips for Cosmos in Lynn County

Direct sow Cosmos outdoors after March 31 in Lynn County when soil has warmed and frost danger has passed.

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

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 →

Frequently Asked Questions

When should I plant Cosmos in Lynn County, TX?

Lynn 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 Lynn County, TX?

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

🌱

Your Lynn County Garden Planner — Free

A 22-page printable planner built for Lynn 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 Lynn 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.