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When to Plant Eggplant in St. Mary's County, MD

St. Mary's County, Maryland Zone 8a May

May in the garden — St. Mary's County, Maryland

We've pulled the most time-sensitive tasks for St. Mary's County, Maryland this May and put them front and centre. Tackle them in order.

Avg. last frost April 5
Avg. first frost November 4
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 14.1 hrs
To set up a strong June, finish these tasks
  • Starting indoors: eggplant
  • First harvests: eggplant

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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.

St. Mary's County, Maryland is in USDA Zone 8a. The average last spring frost is April 5 and the first fall frost is November 4, giving you a growing season of approximately 213 days.

At an elevation of 156 feet, St. Mary's County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 92°F, providing good warmth for Eggplant during the growing season.

St. Mary's County, MD (Zone 8a) Long season
213 days
Last Spring Frost April 5
213 growing days
First Fall Frost November 4

St. Mary's County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (69 days to spare)
Start indoors: Jan 24 Transplant: Apr 11 🍅 Harvest: Jun 20 – Aug 22
Recommended (50%) ✓ Fits season (66 days to spare)
Start indoors: Feb 1 Transplant: Apr 19 🍅 Harvest: Jun 28 – Aug 30
Safe Start (90%) ✓ Fits season (79 days to spare)
Start indoors: Feb 22 Transplant: May 10 🍅 Harvest: Jul 19 – Sep 20

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 St. Mary's County

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

Soil pH

Your soil pH (5.5–6.9) is within Eggplant's preferred range (5.5–7.0).

Soil Texture

The silt loam soil in St. Mary's County is excellent for Eggplant — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Eggplant.

How to Plant Eggplant

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

Succession Planting Eggplant

3
successive plantings in your 213-day season

Sow every 7.4 weeks. Last sowing by Aug 11 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 534 gal / 100 sq ft

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 3.1" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 3.3" 0" ❄️ Dormant
Apr 4.8" 3.3" 1.5" 💧 Light watering
May 4.8" 3.9" 0.9" 💧 Light watering
Jun 4.8" 4.3" 0.5" 💧 Light watering
Jul 4.8" 4" 0.8" 💧 Light watering
Aug 4.8" 4.3" 0.5" 💧 Light watering
Sep 4.8" 3.6" 1.2" 💧 Light watering
Oct 4.8" 3.4" 1.4" 💧 Light watering
Nov 4.8" 2.7" 2.1" 💧 Light watering
Dec 2.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in St. Mary's 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 ~1,425 GDD — county provides 4,047 GDD Excellent fit

Eggplant Planting Timeline — St. Mary's County, MD

Eggplant Planting Calendar

Activity When Date Range
Start Indoors February 1 Feb 1 – Feb 15
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 12 Apr 12 – May 3
Harvest June 28 Jun 28 – Aug 30

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Harvest
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: ideal

🗺️ USDA Zone

Zone 8a

📆 Growing Season

213 days in St. Mary's County

Growing Tips for Eggplant in St. Mary's County

Direct sow Eggplant outdoors after April 05 in St. Mary's County when soil has warmed and frost danger has passed.

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 St. Mary's County, MD?

St. Mary's County is in Zone 8a with an average last frost of April 5. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Mary's County, MD?

St. Mary's County, Maryland is in USDA Hardiness Zone 8a. The average last spring frost is April 5 and first fall frost is November 4.

🌱

Your St. Mary's County Garden Planner — Free

A 24-page printable planner built for St. Mary's 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 St. Mary's County, MD. 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.