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When to Plant Leeks in Blair County, PA

Blair County, Pennsylvania Zone 6b May

Blair County, Pennsylvania gardeners: here's your May plan

Welcome to May in Zone 6b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 25
Avg. first frost October 19
Soil temp (4") 63°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Get leeks seeds going inside

    You're about 24 weeks out from your last frost — the perfect window to get these germinating indoors.

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Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Blair County, Pennsylvania is in USDA Zone 6b. The average last spring frost is April 25 and the first fall frost is October 19, giving you a growing season of approximately 177 days.

At an elevation of 41 feet, Blair County receives approximately 43.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Leeks during the growing season.

Blair County, PA (Zone 6b) Moderate season
177 days
Last Spring Frost April 25
177 growing days
First Fall Frost October 19

Blair County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (11 days to spare)
Start indoors: Mar 13 Transplant: Apr 17 🍅 Harvest: Jul 17 – Oct 2
Recommended (50%) ✓ Fits season (9 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jul 25 – Oct 10
Safe Start (90%) ✓ Fits season (5 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 29

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 Blair County

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

Soil pH

Your soil pH (5.2–6.8) overlaps with Leeks's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.1%). Annual compost additions will help Leeks.

How to Plant Leeks

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

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

Plant Water Budget

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

Monthly Watering Guide for Leeks

Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Leeks Needs Rainfall You Supplement Action
Jan 3.6" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 3.8" 0" ❄️ Dormant
Apr 3.5" 4" 0" ✅ Rainfall sufficient
May 3.5" 4" 0" ✅ Rainfall sufficient
Jun 3.5" 4" 0" ✅ Rainfall sufficient
Jul 3.5" 3.9" 0" ✅ Rainfall sufficient
Aug 3.5" 4.1" 0" ✅ Rainfall sufficient
Sep 3.5" 3.6" 0" ✅ Rainfall sufficient
Oct 3.5" 3.2" 0.3" 💧 Light watering
Nov 3.1" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

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

Leeks 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.

Leeks needs ~2,100 GDD — county provides 3,097 GDD Excellent fit

Leeks Planting Timeline — Blair County, PA

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors April 25 Apr 25 – May 9
Direct Sow April 11 Apr 11 – May 2
Harvest July 25 Jul 25 – Oct 10
Fall Sowing August 10 Aug 10 – Aug 24

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

177 days in Blair County

Growing Tips for Leeks in Blair County

Direct sow Leeks outdoors after April 25 in Blair County when soil has warmed and frost danger has passed.

Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in Blair County, PA?

Blair County is in Zone 6b with an average last frost of April 25. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Blair County, PA?

Blair County, Pennsylvania is in USDA Hardiness Zone 6b. The average last spring frost is April 25 and first fall frost is October 19.

🌱

Your Blair County Garden Planner — Free

A 24-page printable planner built for Blair County (Zone 6b). 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 Blair 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.