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When to Plant Mustard Greens in Mercer County, PA

Mercer County, Pennsylvania Zone 6a May

Your May planting checklist for Mercer County, Pennsylvania

Your Mercer County, Pennsylvania garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 6
Avg. first frost October 17
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Set out mustard greens seedlings

    Frost risk is low now in Mercer County, Pennsylvania. If you've been covering beds overnight, you can stop.

Looking ahead to June
  • Starting indoors: mustard greens
  • First harvests: mustard greens

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Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

Mercer County, Pennsylvania is in USDA Zone 6a. The average last spring frost is May 6 and the first fall frost is October 17, giving you a growing season of approximately 164 days.

At an elevation of 63 feet, Mercer County receives approximately 43.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.

Mercer County, PA (Zone 6a) Moderate season
164 days
Last Spring Frost May 6
164 growing days
First Fall Frost October 17

Mercer County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (67 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jun 3 – Aug 5
Recommended (50%) ✓ Fits season (66 days to spare)
Start indoors: Apr 1 Transplant: May 6 🍅 Harvest: Jun 10 – Aug 12
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Jun 26 – Aug 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 Mercer County

How your county's soil matches Mustard Greens's growing requirements.

Soil pH

Your soil pH (5.1–6.5) is more acidic than Mustard Greens prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Mustard Greens.

How to Plant Mustard Greens

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Mustard Greens

6
successive plantings in your 164-day season

Sow every 3.4 weeks. Last sowing by Aug 28 to harvest before frost.

For a dedicated fall crop, sow by Aug 08.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Mustard Greens

Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mustard Greens Needs Rainfall You Supplement Action
Jan 3.3" 0" ❄️ Dormant
Feb 2.9" 0" ❄️ Dormant
Mar 4" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 3" 3.8" 0" ✅ Rainfall sufficient
Jun 3" 4.2" 0" ✅ Rainfall sufficient
Jul 3" 4.8" 0" ✅ Rainfall sufficient
Aug 3" 3.5" 0" ✅ Rainfall sufficient
Sep 3" 3.1" 0" ✅ Rainfall sufficient
Oct 3" 3.1" 0" ✅ Rainfall sufficient
Nov 3.5" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

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

Mustard Greens 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.

Mustard Greens needs ~520 GDD — county provides 2,132 GDD Excellent fit

Mustard Greens Planting Timeline — Mercer County, PA

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 6 May 6 – May 20
Direct Sow April 22 Apr 22 – May 13
Harvest June 10 Jun 10 – Aug 12
Fall Sowing August 8 Aug 8 – Aug 22

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

164 days in Mercer County

Growing Tips for Mustard Greens in Mercer County

Direct sow Mustard Greens outdoors after May 06 in Mercer County when soil has warmed and frost danger has passed.

Your generous 164.0-day season in Mercer County allows multiple plantings of Mustard Greens. Sow every 15.0 days for continuous harvest.

Common pests for Mustard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mustard Greens in Mercer County, PA?

Mercer County is in Zone 6a with an average last frost of May 6. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mercer County, PA?

Mercer County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is May 6 and first fall frost is October 17.

🌱

Your Mercer County Garden Planner — Free

A 24-page printable planner built for Mercer County (Zone 6a). 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 Mercer County, PA. 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.