kale

Best Planting Times for Kale in Maine

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

Planting Conditions

Maine has a humid continental climate with cold winters and mild summers, falling within USDA Hardiness Zones 3b to 5b. These cooler temperatures are ideal for growing kale, particularly during the spring and fall seasons.

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 Maine’s Largest Cities

CityAverage Last Frost Date
PortlandMay 10
LewistonMay 15
BangorMay 20
South PortlandMay 10
AuburnMay 15
BiddefordMay 12
SanfordMay 14
SacoMay 11
WestbrookMay 10
WatervilleMay 18

Average First Frost Dates for Maine’s Largest Cities

CityAverage First Frost Date
PortlandOctober 5
LewistonOctober 1
BangorOctober 3
South PortlandOctober 5
AuburnOctober 1
BiddefordOctober 3
SanfordOctober 2
SacoOctober 4
WestbrookOctober 5
WatervilleOctober 1

Please note: These dates are averages and can vary from year to year. It’s always a good idea to monitor local weather forecasts and consider your specific location and microclimate when planning your gardening activities.

Starting Kale Indoors

In areas like Portland (Zone 5b), start kale seeds indoors from April 1 to May 1. This timing ensures that seedlings are ready for outdoor transplanting from mid-May to mid-June, after the last frost.


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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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Browse Kale Seeds on Amazon

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.
Grow Lights Image
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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.
Seed Starting Soil Image
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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.
Garden Trowel Image
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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.
Fertilizer Image
Explore Fertilizer on Amazon


Other planting guides for Maine:

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


Transplanting Kale Seedlings

Transplant seedlings outdoors from May 15 to June 15, 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. Maine’s cooler climate may reduce the frequency of watering, but regular monitoring 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 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 Maine’s cooler climate.
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