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When to plant Leeks in Watson,

Plant Leeks in Watson, when soil hits 50°F — usually April 2. Continue planting through April 23 for the spring crop. A second sowing from August 8 to August 22 extends the harvest into fall.

When to Plant Leeks in Watson, IL

Leeks
Watson, IL Zone 6b June

Your June gardening checklist

June is a pivotal month for Watson, IL gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 16
Avg. first frost October 17
Soil temp (4") 68°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
To set up a strong July, finish these tasks
  • First harvests: leeks

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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.

Watson, Illinois is in USDA Zone 6b. The average last spring frost is April 16 and the first fall frost is October 17, giving you a growing season of approximately 184 days.

At an elevation of 953 feet, Effingham County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Watson, IL (Zone 6b) Moderate season
184 days
Last Spring Frost April 16
184 growing days
First Fall Frost October 17

Watson Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Leeks Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Start indoors: Mar 6 Transplant: Apr 10 🍅 Harvest: Jul 10 – Sep 25
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Mar 12 Transplant: Apr 16 🍅 Harvest: Jul 16 – Oct 1
Safe Start (90%) ✓ Fits season (17 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jul 30 – Oct 15

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 Watson

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

Soil pH

Your soil pH (5.8–7.2) overlaps with Leeks's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). 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.

Leeks Water Budget

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

Water stress score is 6/10 — 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 1.5" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 3.5" 3.8" 0" ✅ Rainfall sufficient
May 3.5" 5.1" 0" ✅ Rainfall sufficient
Jun 3.5" 4.5" 0" ✅ Rainfall sufficient
Jul 3.5" 4.6" 0" ✅ Rainfall sufficient
Aug 3.5" 4.5" 0" ✅ Rainfall sufficient
Sep 3.5" 3.8" 0" ✅ Rainfall sufficient
Oct 3.5" 3.3" 0.2" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Effingham 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 ~1,470 GDD — county provides 2,254 GDD Excellent fit

Leeks Planting Timeline — Watson, IL

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 12 Mar 12 – Mar 26
Transplant Outdoors April 16 Apr 16 – Apr 30
Direct Sow April 2 Apr 2 – Apr 23
Harvest July 16 Jul 16 – Oct 1
Fall Sowing August 8 Aug 8 – Aug 22

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Transplant Outdoors Direct Sow
May
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

184 days in Effingham County

Growing Tips for Leeks in Watson

Direct sow Leeks outdoors after April 16 in Effingham 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 →

When should I plant Leeks in Watson, ?

In Watson, , plant Leeks after the last frost (around April 16) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Watson, for Leeks?

Watson sits in USDA Zone 6b. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.

Can Leeks grow in Watson's climate?

Yes — Leeks grows well in Watson's temperate climate. Watson averages a 184-day frost-free season, with last frost around April 16 and first frost around October 17.

🌱

Your Effingham County Garden Planner — Free

A 22-page printable planner built for Effingham 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 Effingham County, IL. Local conditions may vary. Last updated: June 2026.