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When to Plant Tomatoes in Trempealeau County, WI

Trempealeau County, Wisconsin Zone 4b April

Your April game plan for Trempealeau County, Wisconsin

If you only do a handful of things in the garden this April, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 15
Avg. first frost September 30
Soil temp (4") 40°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
May prep starts now
  • Direct-sowing: tomatoes

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Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

Trempealeau County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 30, giving you a growing season of approximately 138 days.

At an elevation of 1,222 feet, Trempealeau County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Tomatoes to ensure they mature before fall.

Trempealeau County, WI (Zone 4b) Short season
138 days
Last Spring Frost May 15
138 growing days
First Fall Frost September 30

Trempealeau County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 7 Transplant: May 30 🍅 Harvest: Aug 1 – Oct 10
Recommended (50%) ✗ May not fit
Start indoors: Mar 13 Transplant: Jun 5 🍅 Harvest: Aug 7 – Oct 16
Safe Start (90%) ✗ May not fit
Start indoors: Mar 20 Transplant: Jun 12 🍅 Harvest: Aug 14 – Oct 23

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 Trempealeau County

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

Soil pH

Your soil pH (5.7–7.2) overlaps with Tomatoes's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Tomatoes will thrive.

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

Succession Planting Tomatoes

2
successive plantings in your 138-day season

Sow every 6.9 weeks. Last sowing by Jul 07 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Tomatoes

Tomatoes 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 Tomatoes Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.1" 0" ❄️ Dormant
May 5.2" 4.4" 0.8" 💧 Light watering
Jun 5.2" 4.9" 0.3" 💧 Light watering
Jul 5.2" 4.2" 1" 💧 Light watering
Aug 5.2" 4.1" 1.1" 💧 Light watering
Sep 5.2" 3.5" 1.7" 💧 Light watering
Oct 3.6" 0" ❄️ Dormant
Nov 2.7" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

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

Tomatoes 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.

Tomatoes needs ~779 GDD — county provides 1,483 GDD Excellent fit

Tomatoes Planting Timeline — Trempealeau County, WI

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors June 5 Jun 5 – Jun 19
Direct Sow May 29 May 29 – Jun 19
Harvest August 7 Aug 7 – Oct 16

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Natural rainfall sufficient

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

138 days in Trempealeau County

Growing Tips for Tomatoes in Trempealeau County

Direct sow Tomatoes outdoors after May 15 in Trempealeau County when soil has warmed and frost danger has passed.

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Trempealeau County

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Trempealeau County, WI?

Trempealeau County is in Zone 4b with an average last frost of May 15. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Trempealeau County, WI?

Trempealeau County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 30.

🌱

Your Trempealeau County Garden Planner — Free

A 24-page printable planner built for Trempealeau County (Zone 4b). 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 Trempealeau County, WI. Local conditions may vary. Last updated: April 2026.

Sources & credits

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