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When to Plant Cucumber in Lake County, IL

Lake County, Illinois Zone 6a May

Your May planting checklist for Lake County, Illinois

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

Avg. last frost April 21
Avg. first frost October 20
Soil temp (4") 59°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Set out cucumber seedlings

    Your last frost (April 21) has passed. These warm-season crops can handle outdoor soil now.

  2. Fire up the seed-starting tray: cucumber

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

To set up a strong June, finish these tasks
  • First harvests: cucumber

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Cucumbers are a warm-season vine crop available in slicing and pickling varieties. They are prolific producers when given warmth, moisture, and a trellis to climb.

Lake County, Illinois is in USDA Zone 6a. The average last spring frost is April 21 and the first fall frost is October 20, giving you a growing season of approximately 182 days.

At an elevation of 1,080 feet, Lake County receives approximately 33.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Cucumber to ensure they mature before fall.

Lake County, IL (Zone 6a) Moderate season
182 days
Last Spring Frost April 21
182 growing days
First Fall Frost October 20
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Lake County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Mar 12 Transplant: Apr 30 🍅 Harvest: Jun 25 – Aug 20
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Mar 17 Transplant: May 5 🍅 Harvest: Jun 30 – Aug 25
Safe Start (90%) ✓ Fits season (54 days to spare)
Start indoors: Apr 4 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 12

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 Lake County

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

Soil pH

Your soil pH (6.2–6.9) is within Cucumber's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Cucumber.

How to Plant Cucumber

0.5"
Planting Depth
24"
Between Plants
48"
Between Rows

Succession Planting Cucumber

4
successive plantings in your 182-day season

Sow every 5.7 weeks. Last sowing by Aug 11 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,413 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Cucumber

Cucumber needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Cucumber Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 6.5" 3.3" 3.2" 💧 Light watering
May 6.5" 3.9" 2.6" 💧 Light watering
Jun 6.5" 4.4" 2.1" 💧 Light watering
Jul 6.5" 3.3" 3.2" 💧 Light watering
Aug 6.5" 3.4" 3.1" 💧 Light watering
Sep 6.5" 3.3" 3.2" 💧 Light watering
Oct 6.5" 2.8" 3.7" 🚿 Regular watering
Nov 2.3" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Cucumber 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.

Cucumber needs ~735 GDD — county provides 2,229 GDD Excellent fit

Cucumber Planting Timeline — Lake County, IL

Cucumber Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 – Mar 31
Transplant Outdoors May 5 May 5 – May 19
Direct Sow April 28 Apr 28 – May 19
Harvest June 30 Jun 30 – Aug 25

Plant 0.5" deep · 24" apart · Rows 48" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

182 days in Lake County

Growing Tips for Cucumber in Lake County

Direct sow Cucumber outdoors after April 21 in Lake County when soil has warmed and frost danger has passed.

Common pests for Cucumber in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost or start indoors 3 weeks early. Provide a trellis for vining types to save space and improve air circulation. Harvest frequently to encourage production.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Sage

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cucumber in Lake County, IL?

Lake County is in Zone 6a with an average last frost of April 21. Plan your Cucumber planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lake County, IL?

Lake County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 21 and first fall frost is October 20.

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Your Lake County Garden Planner — Free

A 24-page printable planner built for Lake 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Lake County, IL. 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.