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When to Plant Borage in Cobb County, GA

Cobb County, Georgia Zone 8a May

Your May game plan for Cobb County, Georgia

Welcome to May in Zone 8a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost March 31
Avg. first frost November 1
Soil temp (4") 67°F
Watering Low
Pest pressure Moderate
Daylight 13.8 hrs
  1. Begin indoor sowing: borage

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

  2. Basket week: borage

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

A few tasks this May that'll pay off in June
  • First harvests: borage

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Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.

Cobb County, Georgia is in USDA Zone 8a. The average last spring frost is March 31 and the first fall frost is November 1, giving you a growing season of approximately 215 days.

At an elevation of 387 feet, Cobb County receives approximately 57.2 inches of rainfall annually with predominantly clay loam soil. Summer highs average 89°F, providing good warmth for Borage during the growing season. Clay soil retains moisture well for Borage, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Borage root diseases.

Cobb County, GA (Zone 8a) Long season
215 days
Last Spring Frost March 31
215 growing days
First Fall Frost November 1

Cobb County Soil Profile

Soil Type

Clay Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (119 days to spare)
Start indoors: Feb 16 Transplant: Mar 16 🍅 Harvest: May 11 – Jun 29
Recommended (50%) ✓ Fits season (117 days to spare)
Start indoors: Feb 24 Transplant: Mar 24 🍅 Harvest: May 19 – Jul 7
Safe Start (90%) ✓ Fits season (122 days to spare)
Start indoors: Mar 13 Transplant: Apr 10 🍅 Harvest: Jun 5 – Jul 24

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 Cobb County

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

Soil pH

Your soil pH (5.3–6.5) is more acidic than Borage prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The clay loam soil in Cobb County is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Borage prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Borage.

How to Plant Borage

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Borage

5
successive plantings in your 215-day season

Sow every 5.7 weeks. Last sowing by Sep 02 to harvest before frost.

For a dedicated fall crop, sow by Aug 23.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/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 Borage

Borage 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 Borage Needs Rainfall You Supplement Action
Jan 4.2" 0" ❄️ Dormant
Feb 4" 0" ❄️ Dormant
Mar 2.2" 6" 0" ✅ Rainfall sufficient
Apr 2.2" 4.7" 0" ✅ Rainfall sufficient
May 2.2" 3.9" 0" ✅ Rainfall sufficient
Jun 2.2" 5.8" 0" ✅ Rainfall sufficient
Jul 2.2" 5.5" 0" ✅ Rainfall sufficient
Aug 2.2" 5.2" 0" ✅ Rainfall sufficient
Sep 2.2" 4.7" 0" ✅ Rainfall sufficient
Oct 2.2" 3.7" 0" ✅ Rainfall sufficient
Nov 2.2" 4.3" 0" ✅ Rainfall sufficient
Dec 5.2" 0" ❄️ Dormant

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

Borage 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.

Borage needs ~921 GDD — county provides 3,601 GDD Excellent fit

Borage Planting Timeline — Cobb County, GA

Borage Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 – Mar 10
Transplant Outdoors March 24 Mar 24 – Apr 7
Direct Sow March 17 Mar 17 – Apr 7
Harvest May 19 May 19 – Jul 7
Fall Sowing August 23 Aug 23 – Sep 6

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 8a

📆 Growing Season

215 days in Cobb County

Growing Tips for Borage in Cobb County

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

With Cobb County's clay soil (26% clay), work in 3-4 inches of compost before planting Borage. Avoid tilling when soil is wet to prevent compaction.

With 57" of annual rainfall in Cobb County, ensure good drainage for Borage — excess moisture can promote root rot and fungal diseases.

General growing tips

Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Borage in Cobb County, GA?

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

What planting zone is Cobb County, GA?

Cobb County, Georgia is in USDA Hardiness Zone 8a. The average last spring frost is March 31 and first fall frost is November 1.

🌱

Your Cobb County Garden Planner — Free

A 24-page printable planner built for Cobb 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Cobb County, GA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.