Blog

When to Plant Eggplant in Robertson County, TX

Robertson County, Texas Zone 9a May

Your May gardening checklist

Each item below is timed to Robertson County, Texas's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost March 7
Avg. first frost November 16
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.6 hrs
  1. Collect eggplant at their peak

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

Looking ahead to June
  • First harvests: eggplant

Instant PDF download. No spam, unsubscribe any time.

Eggplant is a heat-loving solanaceous crop that produces glossy fruits in purple, white, or striped varieties. It requires long, warm growing seasons for best production.

Robertson County, Texas is in USDA Zone 9a. The average last spring frost is March 7 and the first fall frost is November 16, giving you a growing season of approximately 254 days.

At an elevation of 85 feet, Robertson County receives approximately 61.1 inches of rainfall annually with predominantly clay soil. Summer highs average 93°F, providing good warmth for Eggplant during the growing season. Clay soil retains moisture well for Eggplant, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Eggplant root diseases.

Robertson County, TX (Zone 9a) Long season
254 days
Last Spring Frost March 7
254 growing days
First Fall Frost November 16

Robertson County Soil Profile

Soil Type

Clay

Soil pH

6.8-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (116 days to spare)
Start indoors: Jan 17 Transplant: Mar 7 🍅 Harvest: May 16 – Jul 18
Recommended (50%) ✓ Fits season (114 days to spare)
Start indoors: Jan 24 Transplant: Mar 14 🍅 Harvest: May 23 – Jul 25
Safe Start (90%) ✓ Fits season (108 days to spare)
Start indoors: Feb 24 Transplant: Apr 14 🍅 Harvest: Jun 23 – Aug 25

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 Robertson County

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

Soil pH

Your soil pH (6.8–8.0) is more alkaline than Eggplant prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (45% clay) in Robertson County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Eggplant.

How to Plant Eggplant

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Eggplant

4
successive plantings in your 254-day season

Sow every 7.4 weeks. Last sowing by Aug 23 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 243 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Eggplant

Eggplant needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Eggplant Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 2.2" 0" ❄️ Dormant
Mar 4.8" 4.3" 0.5" 💧 Light watering
Apr 4.8" 5.6" 0" ✅ Rainfall sufficient
May 4.8" 10" 0" ✅ Rainfall sufficient
Jun 4.8" 8.4" 0" ✅ Rainfall sufficient
Jul 4.8" 8.3" 0" ✅ Rainfall sufficient
Aug 4.8" 8.2" 0" ✅ Rainfall sufficient
Sep 4.8" 5.2" 0" ✅ Rainfall sufficient
Oct 4.8" 3.7" 1.1" 💧 Light watering
Nov 4.8" 2.3" 2.5" 🚿 Regular watering
Dec 1.6" 0" ❄️ Dormant

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

Eggplant 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.

Eggplant needs ~1,481 GDD — county provides 5,016 GDD Excellent fit

Eggplant Planting Timeline — Robertson County, TX

Eggplant Planting Calendar

Activity When Date Range
Start Indoors January 24 Jan 24 – Feb 7
Transplant Outdoors March 14 Mar 14 – Mar 28
Direct Sow March 7 Mar 7 – Mar 28
Harvest May 23 May 23 – Jul 25

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Only during dry spells

📅 Days to Maturity

65–85 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9a

📆 Growing Season

254 days in Robertson County

Growing Tips for Eggplant in Robertson County

Direct sow Eggplant outdoors after March 07 in Robertson County when soil has warmed and frost danger has passed.

With Robertson County's clay soil (45% clay), work in 3-4 inches of compost before planting Eggplant. Avoid tilling when soil is wet to prevent compaction.

Common pests for Eggplant in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 8-10 weeks before last frost. Transplant only after nighttime temperatures stay above 55F. Mulch to retain moisture and warmth around roots.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Kohlrabi

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Eggplant in Robertson County, TX?

Robertson County is in Zone 9a with an average last frost of March 7. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Robertson County, TX?

Robertson County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 7 and first fall frost is November 16.

🌱

Your Robertson County Garden Planner — Free

A 24-page printable planner built for Robertson County (Zone 9a). 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 Robertson County, TX. 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.