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When to plant Zucchini in Putnam County, IL

Zucchini planted in Putnam County between April 28 and May 19 matures in 45–60 days — well before the October 13 first frost.

When to Plant Zucchini in Putnam County, IL

Zucchini
Putnam County, Illinois Zone 5b July

Your July game plan for Putnam County, Illinois

We've pulled the most time-sensitive tasks for Putnam County, Illinois this July and put them front and centre. Tackle them in order.

Avg. last frost April 21
Avg. first frost October 13
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
  1. Basket week: zucchini

    If you can't use it all right away, check the food-preservation section of your planner.

Before August arrives, get these ready
  • First harvests: zucchini

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Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Putnam County, Illinois is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 13, giving you a growing season of approximately 175 days.

At an elevation of 582 feet, Putnam County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Zucchini during the growing season.

Putnam County, IL (Zone 5b) Moderate season
175 days
Last Spring Frost April 21
175 growing days
First Fall Frost October 13

Putnam County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.7

Drainage

Well Drained

Zucchini Planting Risk Windows

Early Start (70% safe) ✓ Fits season (56 days to spare)
Start indoors: Mar 12 Transplant: Apr 30 🍅 Harvest: Jun 18 – Aug 13
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Mar 17 Transplant: May 5 🍅 Harvest: Jun 23 – Aug 18
Safe Start (90%) ✓ Fits season (53 days to spare)
Start indoors: Apr 4 Transplant: May 23 🍅 Harvest: Jul 11 – Sep 5

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 Putnam County

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

Soil pH

Your soil pH (6.0–6.7) is within Zucchini's preferred range (6.0–7.5).

Soil Texture

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

Drainage

Drainage is adequate for Zucchini.

Organic Matter

Organic matter is excellent (4.3%) — Zucchini will thrive.

How to Plant Zucchini

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Zucchini

4
successive plantings in your 175-day season

Sow every 5.1 weeks. Last sowing by Aug 14 to harvest before frost.

Zucchini Water Budget

Plant needs
1.2″/week
Rainfall provides
1.0″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 878 gal / 100 sq ft

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 5.2" 3.6" 1.6" 💧 Light watering
May 5.2" 4.3" 0.9" 💧 Light watering
Jun 5.2" 5.2" 0" ✅ Rainfall sufficient
Jul 5.2" 5" 0.2" 💧 Light watering
Aug 5.2" 4.3" 0.9" 💧 Light watering
Sep 5.2" 3.3" 1.9" 💧 Light watering
Oct 5.2" 3.3" 1.9" 💧 Light watering
Nov 3.2" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

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

Zucchini 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.

Zucchini needs ~801 GDD — county provides 2,668 GDD Excellent fit

Zucchini Planting Timeline — Putnam County, IL

Zucchini 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 23 Jun 23 – Aug 18

Plant 1" deep · 30" apart · Rows 42" 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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 1-2 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

175 days in Putnam County

Growing Tips for Zucchini in Putnam County

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

Your generous 175.0-day season in Putnam County allows multiple plantings of Zucchini. Sow every 22.0 days for continuous harvest.

Common pests for Zucchini 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. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Putnam County, IL?

Putnam County is in Zone 5b with an average last frost of April 21. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Putnam County, IL?

Putnam County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 21 and first fall frost is October 13.

When should I plant Zucchini in Putnam County, IL?

In Putnam County, IL, plant Zucchini after the last frost (around April 21) and before the first frost (around October 13). Best results when soil holds above 50°F.

What growing zone is Putnam County, IL for Zucchini?

Putnam County sits in USDA Zone 5b. Zucchini grows reliably in zones 3a through 11b, so it's a good fit here.

Can Zucchini grow in Putnam County's climate?

Yes — Zucchini grows well in Putnam County's temperate climate. Putnam County averages a 175-day frost-free season, with last frost around April 21 and first frost around October 13.

🌱

Your Putnam County Garden Planner — Free

A 22-page printable planner built for Putnam County (Zone 5b). 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 Putnam County, IL. Local conditions may vary. Last updated: July 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.