Planting Guides

When to Plant Kale in Milwaukee: Complete Guide + Best Varieties for Zone 5b

Milwaukee, Wisconsin

USDA Zone 5b

Last Frost: May 15

Last updated: October 30, 2025

Learn when to plant kale in Milwaukee with specific dates for Zone 5b. Compare 5 varieties, get a complete timeline, and discover which kale grow best in Wisconsin.

PPatricia "Pat" O'Brien

October 30, 2025

Kale plants thriving in Milwaukee Zone 5b garden during fall harvest season — — Image © PlantReference.org 2026

Quick Answer

Plant kale seeds August 1-15 for fall harvest in Milwaukee's Zone 5b. Fall plantings produce sweeter kale after September frosts.

TL;DR

Milwaukee gardeners should plant kale seeds August 1-15 for fall harvest and April 1-15 for spring crops in Zone 5b. Fall planting produces superior flavor after September frost sweetens the leaves. Start seeds indoors March 15 for spring transplants or direct sow when soil temperature reaches 45°F (7°C).

Frequently Asked Questions

When should I plant kale seeds in Milwaukee?

Plant kale seeds August 1-15 for fall harvest and April 15-30 for spring crops in Milwaukee's Zone 5b. Fall planting consistently produces superior flavor because September frosts convert starches to sugars, making leaves sweet and tender. Spring planting works but must be harvested before summer heat causes bolting.

What are the best kale varieties for Milwaukee winters?

Brassica oleracea 'Winterbor' and Brassica oleracea 'Redbor' survive Milwaukee winters with minimal protection. These varieties tolerate temperatures down to 0°F (-18°C) with snow cover or row covers. Brassica oleracea 'Lacinato' also overwinters well but needs more protection during extreme cold snaps.

Can I grow kale year-round in Milwaukee?

No, Milwaukee's Zone 5b climate limits year-round production. Grow kale spring through fall (April-November), with peak quality October-November after frost sweetening. Summer growing fails due to heat stress and bolting. Winter survival requires cold-hardy varieties and protection during extreme cold.

How do I prevent kale from bolting in Milwaukee summers?

Choose bolt-resistant varieties like Brassica oleracea 'Red Russian' for spring plantings. Harvest leaves frequently when small to delay flowering. Provide afternoon shade during heat waves above 80°F (27°C). Most importantly, focus on fall plantings instead—Milwaukee summers aren't ideal for kale growing.

When does kale taste best in Milwaukee?

Kale tastes sweetest after Milwaukee's first frost around September 30. Cold temperatures trigger starch-to-sugar conversion, eliminating bitterness and creating sweet, tender leaves. Peak flavor continues through November and December during consistent cold weather. Spring kale never achieves the same sweetness as frost-kissed fall crops.

How do I protect kale from Milwaukee winters?

Mulch heavily around plants with 4-6 inches of straw or leaves. Use floating row covers during extreme cold below 0°F (-18°C). Choose cold-hardy varieties like Brassica oleracea 'Winterbor'. Plant in protected locations away from prevailing northwest winds. Snow cover actually insulates plants and extends harvest season.

What pests attack kale in Milwaukee gardens?

Cabbage worms (green caterpillars) are the primary pest, creating large holes in leaves. Control with floating row covers or weekly Bt spray during May-July peak season. Flea beetles damage young seedlings with shot-hole feeding. Aphids cluster on leaf undersides during humid summers—spray off with strong water weekly.

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Tagged with

#Milwaukee gardening #Zone 5b vegetables #Wisconsin kale growing #fall vegetables #frost-hardy crops #cold season gardening #kale varieties #winter harvest #succession planting #Milwaukee frost dates

Written By

Patricia "Pat" O'Brien

Pat has been gardening in Milwaukee for over thirty years, through every kind of Wisconsin weather. She worked as a school librarian and started gardening seriously when her kids were small—she wanted them to know where food came from. Now retired, she's a certified Master Gardener and runs the plant sale at her local garden club every spring. She specializes in cold-hardy perennials, native wildflower meadows, and the art of getting a vegetable garden producing in Wisconsin's short but intense growing season. Pat is practical and patient—she's seen enough Wisconsin winters to know that gardening here is a long game, and she writes with the steady confidence of someone who's been doing this a long time.