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When to Plant Leeks in Boone County, KY

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.

Boone County, Kentucky is in USDA Zone 6a. The average last spring frost is April 19 and the first fall frost is October 21, giving you a growing season of approximately 185 days.

At an elevation of 2,587 feet, Boone County receives approximately 51 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89ยฐF, providing good warmth for Leeks during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Leeks root diseases.

Boone County, KY (Zone 6a) Moderate season
185 days
Last Spring Frost April 19
185 growing days
First Fall Frost October 21

Boone County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Mar 7 Transplant: Apr 11 🍅 Harvest: Jul 11 – Sep 26
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Mar 15 Transplant: Apr 19 🍅 Harvest: Jul 19 – Oct 4
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Aug 8 – Oct 24

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 Boone County

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

Soil pH

Your soil pH (5.7โ€“6.5) overlaps with Leeks's range (6.0โ€“7.0), though not a perfect match.

Soil Texture

The silt loam soil in Boone County is excellent for Leeks โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). 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
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

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 โ€” 4.7" 0" โ„๏ธ Dormant
Feb โ€” 4.1" 0" โ„๏ธ Dormant
Mar โ€” 5.2" 0" โ„๏ธ Dormant
Apr 3.5" 3.7" 0" โœ… Rainfall sufficient
May 3.5" 3.6" 0" โœ… Rainfall sufficient
Jun 3.5" 5.1" 0" โœ… Rainfall sufficient
Jul 3.5" 5.2" 0" โœ… Rainfall sufficient
Aug 3.5" 4.4" 0" โœ… Rainfall sufficient
Sep 3.5" 4.3" 0" โœ… Rainfall sufficient
Oct 3.5" 3" 0.5" ๐Ÿ’ง Light watering
Nov โ€” 3.9" 0" โ„๏ธ Dormant
Dec โ€” 3.9" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Boone County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 ~2,010 GDD — county provides 3,098 GDD Excellent fit

Leeks Planting Timeline โ€” Boone County, KY

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 โ€“ Mar 29
Transplant Outdoors April 19 Apr 19 โ€“ May 3
Direct Sow April 5 Apr 5 โ€“ Apr 26
Harvest July 19 Jul 19 โ€“ Oct 4
Fall Sowing August 12 Aug 12 โ€“ Aug 26

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

Month-by-Month Timeline

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

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.8"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

90โ€“150 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 6a

๐Ÿ“† Growing Season

185 days in Boone County

Growing Tips for Leeks in Boone County

Direct sow Leeks outdoors after April 19 in Boone 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 Boone County, KY?

Boone County is in Zone 6a with an average last frost of April 19. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Boone County, KY?

Boone County, Kentucky is in USDA Hardiness Zone 6a. The average last spring frost is April 19 and first fall frost is October 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Boone County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Boone County, KY. Local conditions may vary. Last updated: April 2026.