Best Planting Times for Kale in Wisconsin

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingMarch 15 – April 15
Transplant OutdoorsMay 1 – June 1
Fall PlantingDirect Sow OutdoorsJuly 15 – August 15

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Useful Tools for Starting Kale Indoors

Using the right tools can save you time and increase your success rate.

Seeds

Quality seeds lead to better germination and healthier plants. Starting with high-quality seeds gives your kale the best chance to thrive from the very beginning.
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Planting Trays

Planting trays help you organize your seedlings and ensure they have enough space to grow before you transplant them outdoors. This makes the process more efficient and increases the chances of strong, healthy plants.
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Grow Lights

Grow lights are essential if you don’t have enough natural sunlight. They provide your seedlings with the light they need to grow strong and healthy, even in less-than-ideal conditions.
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Seed Starting Soil

Using light, fine soil specifically designed for seed starting helps young roots establish quickly and promotes healthy growth. It’s an easy way to give your seedlings the best start possible.
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Garden Tools and Fertilizer

Garden Trowel

A garden trowel is a handy tool that makes transplanting your seedlings easier and more precise, ensuring that each plant is placed at the right depth without damaging the roots.
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Soil and Fertilizer

Fertilizer is essential for enhancing growth, especially if your soil is nutrient-poor. By enriching the soil, you give your kale plants the nutrients they need to grow robust and produce a bountiful harvest.
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Other planting guides for Wisconsin:

Any questions on growing kale? Visit our forum to discuss: Growing Kale

Planting Conditions

Wisconsin experiences a humid continental climate, characterized by cold winters and warm summers, with USDA Hardiness Zones ranging from 3b to 5b. These conditions are favorable for growing cool-season crops like kale, particularly in the spring and fall.

Plant kale outdoors approximately 4-6 weeks before the last frost in spring, and 6-8 weeks before the first frost in fall.

Average Last Frost Dates for Wisconsin’s Largest Cities

CityAverage Last Frost Date
MilwaukeeMay 1
MadisonMay 10
Green BayMay 15
KenoshaMay 1
RacineMay 1
AppletonMay 15
WaukeshaMay 10
Eau ClaireMay 20
OshkoshMay 15
JanesvilleMay 10

Average First Frost Dates for Wisconsin’s Largest Cities

CityAverage First Frost Date
MilwaukeeOctober 15
MadisonOctober 10
Green BayOctober 5
KenoshaOctober 15
RacineOctober 15
AppletonOctober 5
WaukeshaOctober 10
Eau ClaireOctober 1
OshkoshOctober 5
JanesvilleOctober 10

Please note: These dates are averages and can vary from year to year.

Starting Kale Indoors

In areas like Milwaukee (Zone 5b), start kale seeds indoors from March 15 to April 15. This timing ensures that seedlings are ready for outdoor transplanting from early May to early June, after the last frost.

Transplanting Kale Seedlings

Transplant seedlings outdoors from May 1 to June 1, ensuring soil temperatures are consistently above 45°F. Space seedlings 12-18 inches apart in rows at least 18 inches apart to allow for good air circulation and sunlight exposure.

General Care and Maintenance

Watering:

  • Water deeply and consistently to keep the soil evenly moist. Wisconsin’s warm summers can dry out the soil quickly, so regular watering is essential.
  • Water at the base of the plants to prevent wetting the foliage, which helps reduce the risk of fungal diseases.

Fertilizing:

  • Apply a balanced fertilizer at planting and again when the leaves begin to develop. Adding compost to the soil before planting can improve fertility and moisture retention.

Pest and Disease Management:

  • Monitor for common pests like aphids, flea beetles, and cabbage worms. The cooler, humid climate can also encourage fungal diseases, so vigilance is necessary.
  • Use organic or integrated pest management strategies to protect your plants from pests and diseases.

Harvesting Kale:

  • Harvest kale leaves when they are large enough to eat but still tender. Regular harvesting encourages new growth and extends the harvesting season, particularly in Wisconsin’s cooler fall climate.
BeeJay
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