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When to Plant Celery in Charles County, MD

Charles County, Maryland Zone 7b May

May in Charles County, Maryland — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Charles County, Maryland.

Avg. last frost March 29
Avg. first frost November 14
Soil temp (4") 68°F
Watering Moderate
Pest pressure Moderate
Daylight 14.1 hrs
  1. Get celery seeds going inside

    Label every cell. You will absolutely forget which is which otherwise.

Before June arrives, get these ready
  • First harvests: celery

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Celery is a marshland plant that requires consistent moisture and cool temperatures to produce crisp, flavorful stalks. It is a rewarding but demanding garden crop.

Charles County, Maryland is in USDA Zone 7b. The average last spring frost is March 29 and the first fall frost is November 14, giving you a growing season of approximately 230 days.

At an elevation of 382 feet, Charles County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Celery during the growing season.

Charles County, MD (Zone 7b) Long season
230 days
Last Spring Frost March 29
230 growing days
First Fall Frost November 14

Charles County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (85 days to spare)
Start indoors: Feb 17 Transplant: Mar 24 🍅 Harvest: Jun 16 – Aug 11
Recommended (50%) ✓ Fits season (90 days to spare)
Start indoors: Feb 22 Transplant: Mar 29 🍅 Harvest: Jun 21 – Aug 16
Safe Start (90%) ✓ Fits season (97 days to spare)
Start indoors: Mar 12 Transplant: Apr 16 🍅 Harvest: Jul 9 – Sep 3

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 Charles County

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

Soil pH

Your soil pH (5.7–6.8) overlaps with Celery's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Charles County is excellent for Celery — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Celery.

How to Plant Celery

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Celery

3
successive plantings in your 230-day season

Sow every 9.1 weeks. Last sowing by Jul 17 to harvest before frost.

For a dedicated fall crop, sow by Sep 05.

Plant Water Budget

Plant needs
1.3″/week
Rainfall provides
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,229 gal / 100 sq ft

Monthly Watering Guide for Celery

Celery needs approximately 1.3 inches of water per week (5.6" per month). Here's how your county's rainfall compares month by month.

Month Celery Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 5.6" 3.2" 2.4" 💧 Light watering
Apr 5.6" 3.1" 2.5" 💧 Light watering
May 5.6" 3.4" 2.2" 💧 Light watering
Jun 5.6" 3.4" 2.2" 💧 Light watering
Jul 5.6" 4" 1.6" 💧 Light watering
Aug 5.6" 3.8" 1.8" 💧 Light watering
Sep 5.6" 3.4" 2.2" 💧 Light watering
Oct 5.6" 2.9" 2.7" 💧 Light watering
Nov 5.6" 2.8" 2.8" 🚿 Regular watering
Dec 2.6" 0" ❄️ Dormant

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

Celery 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.

Celery needs ~1,825 GDD — county provides 4,197 GDD Excellent fit

Celery Planting Timeline — Charles County, MD

Celery Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 – Mar 8
Transplant Outdoors March 29 Mar 29 – Apr 12
Direct Sow March 15 Mar 15 – Apr 5
Harvest June 21 Jun 21 – Aug 16
Fall Sowing September 5 Sep 5 – Sep 19

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · 1-2 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

230 days in Charles County

Growing Tips for Celery in Charles County

Direct sow Celery outdoors after March 29 in Charles County when soil has warmed and frost danger has passed.

Common pests for Celery in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Keep soil consistently moist and never let it dry out. Blanch stalks by mounding soil or using collars for milder flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Celery in Charles County, MD?

Charles County is in Zone 7b with an average last frost of March 29. Plan your Celery planting based on this frost date — see the calendar above for exact timing.

What planting zone is Charles County, MD?

Charles County, Maryland is in USDA Hardiness Zone 7b. The average last spring frost is March 29 and first fall frost is November 14.

🌱

Your Charles County Garden Planner — Free

A 24-page printable planner built for Charles County (Zone 7b). 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 Charles 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.