Best Time To Plant Kale In Minnesota

Minnesota’s cold winters mean kale should be planted in early spring, with a second crop in midsummer. Finding the best time to plant kale in minnesota is key to getting a long harvest from this cold-hardy green. You can start seeds indoors or sow them directly in the garden once the soil is workable.

Kale thrives in cool weather and actually tastes sweeter after a light frost. This makes it one of the most reliable vegetables for Minnesota’s short growing season. Whether you are a beginner or a seasoned gardener, timing your planting right will give you fresh leaves from May through November.

Understanding Minnesota’s Growing Zones

Minnesota spans USDA hardiness zones 3a to 5a. This means your last frost date can vary by several weeks depending on where you live. Southern Minnesota usually has a longer growing season than the northern part of the state.

For most of the state, the last spring frost occurs between mid-April and late May. The first fall frost typically arrives between mid-September and early October. Kale can handle light frosts, but knowing your local frost dates helps you plan better.

Key Frost Dates For Minnesota Regions

Northern Minnesota (Zone 3a-3b): Last frost around May 20-31, first frost around September 10-20.
Central Minnesota (Zone 4a-4b): Last frost around May 10-20, first frost around September 20-30.
Southern Minnesota (Zone 5a): Last frost around April 20-May 5, first frost around October 1-10.

Kale seeds germinate in soil as cold as 40°F. You can plant them 4 to 6 weeks before your last frost date. This gives you a head start on the season.

The ideal window for spring planting is from late March to early May, depending on your zone. For a fall crop, plant in late July to early August. This two-crop strategy works perfectly for Minnesota’s climate.

Spring-planted kale will produce leaves through June and early July. Summer heat can make the leaves tough and bitter, but the plant will bounce back when temperatures cool down. Fall-planted kale often tastes better because of the cooler weather and light frosts.

Spring Planting Schedule By Zone

Zone 3a-3b (Northern MN): Start seeds indoors in late March. Transplant outdoors in early to mid-May. Direct sow seeds in mid-May.
Zone 4a-4b (Central MN): Start seeds indoors in mid-March. Transplant outdoors in late April to early May. Direct sow seeds in late April.
Zone 5a (Southern MN): Start seeds indoors in early March. Transplant outdoors in mid-April. Direct sow seeds in early to mid-April.

If you direct sow, plant seeds about 1/2 inch deep and 12 to 18 inches apart. Thin seedlings to 12 inches apart once they have two sets of true leaves. Kale needs full sun but can tolerate partial shade, especially in warmer parts of the state.

Fall Planting Schedule For Minnesota

For a fall harvest, plant kale seeds directly in the garden 6 to 8 weeks before your first fall frost. This usually means late July to early August in most of Minnesota. The plants will mature as temperatures drop, giving you sweet, tender leaves.

Northern MN: Plant fall kale by late July.
Central MN: Plant fall kale by early August.
Southern MN: Plant fall kale by mid-August.

Fall-planted kale can survive under snow and be harvested well into November or even December. A layer of row cover or mulch helps extend the season even further.

Preparing Your Soil For Kale

Kale grows best in well-drained soil rich in organic matter. Before planting, test your soil pH. Kale prefers a pH between 6.0 and 7.5. If your soil is too acidic, add lime a few weeks before planting.

Work in 2 to 4 inches of compost or aged manure into the top 6 inches of soil. This improves drainage and provides nutrients. Avoid fresh manure, as it can burn young roots.

Soil Preparation Steps

Clear the area of weeds and debris.
Loosen the soil to a depth of 8 to 10 inches.
Mix in compost or a balanced fertilizer like 10-10-10.
Rake the bed smooth and water it well.

Kale is a heavy feeder, so consider side-dressing with compost or a nitrogen-rich fertilizer every 4 to 6 weeks during the growing season. This keeps the leaves green and productive.

Starting Kale Seeds Indoors

Starting seeds indoors gives you a head start, especially in northern Minnesota where the growing season is short. Use seed-starting mix and small pots or trays. Plant seeds 1/4 inch deep and keep the soil moist.

Place the trays in a warm spot, around 65°F to 75°F. Seedlings should emerge in 5 to 10 days. Once they have two true leaves, move them to a cooler location with bright light. Harden them off by gradually exposing them to outdoor conditions over a week.

Indoor Seed Starting Timeline

Start seeds: 4 to 6 weeks before last frost.
Transplant outdoors: 2 to 4 weeks before last frost.
Harden off: Start 7 to 10 days before transplanting.

When transplanting, space seedlings 12 to 18 inches apart in rows 18 to 24 inches apart. Water them well after planting and provide shade for a few days if the weather is hot.

Direct Sowing Kale Seeds

Direct sowing is easier and works well for fall crops. Wait until the soil temperature is at least 40°F. In Minnesota, this usually happens in April for spring planting and late July for fall planting.

Sow seeds 1/2 inch deep and 1 inch apart. Cover lightly with soil and water gently. Keep the soil moist until seedlings emerge. Thin them to 12 inches apart when they are 3 to 4 inches tall.

Tips For Direct Sowing Success

Soak seeds in water for 12 hours before planting to speed germination.
Plant in rows or blocks for easier weeding.
Use a light mulch to retain moisture and suppress weeds.
Water regularly, especially during dry spells.

Direct-sown kale often develops stronger roots than transplanted kale. This makes it more drought-tolerant and better able to handle Minnesota’s temperature swings.

Caring For Your Kale Plants

Kale is relatively low-maintenance, but consistent care ensures a good harvest. Water deeply once or twice a week, providing about 1 to 1.5 inches of water per week. Mulch around the plants to keep the soil cool and moist.

Fertilize every 4 to 6 weeks with a balanced fertilizer or compost tea. Watch for pests like aphids, cabbage worms, and flea beetles. Use row covers or insecticidal soap if needed.

Common Kale Pests In Minnesota

Aphids: Small green or black insects on leaf undersides. Spray with water or use neem oil.
Cabbage worms: Green caterpillars that chew holes in leaves. Handpick or use Bt (Bacillus thuringiensis).
Flea beetles: Tiny jumping beetles that create small holes. Use row covers or diatomaceous earth.

Kale is generally disease-resistant, but avoid overhead watering to prevent fungal issues. Good air circulation also helps keep plants healthy.

Harvesting Kale At The Right Time

You can start harvesting kale when the leaves are about the size of your hand. Pick the outer leaves first, leaving the inner ones to continue growing. This method gives you a continuous supply for weeks.

For spring-planted kale, start harvesting in late May or early June. Fall-planted kale can be harvested from September through November. After a frost, the leaves become sweeter and less bitter.

Harvesting Tips

Harvest in the morning when leaves are crisp.
Use a sharp knife or scissors to cut leaves at the stem.
Leave at least 4 to 5 inner leaves for regrowth.
Stop harvesting when the plant starts to flower (bolting).

Kale can survive temperatures as low as 10°F. If you cover the plants with a thick layer of straw or row cover, you can harvest fresh kale even in December. Some gardeners in Minnesota have picked kale from under the snow.

Extending The Growing Season

Minnesota’s short summers mean you need to maximize your growing window. Use cold frames, hoop houses, or row covers to protect plants from early frosts. These structures can add 4 to 6 weeks to your harvest season.

For fall and winter harvests, plant kale in a sheltered location near a south-facing wall. The wall absorbs heat during the day and releases it at night, keeping the plants warmer. Mulch heavily around the base to insulate the roots.

Season Extension Methods

Row covers: Lightweight fabric that protects from frost and pests.
Cold frames: Simple boxes with a glass or plastic top that trap heat.
Hoop houses: PVC or metal hoops covered with greenhouse plastic.
Mulch: Straw, leaves, or wood chips to insulate soil.

With these methods, you can enjoy fresh kale from your garden for 8 to 10 months of the year. Some varieties like ‘Winterbor’ and ‘Red Russian’ are especially cold-hardy.

Best Kale Varieties For Minnesota

Choosing the right variety makes a big difference in your success. Look for cold-hardy types that can handle Minnesota’s temperature extremes. Here are some top choices:

Winterbor: A curly kale that is very cold-tolerant. It survives down to -10°F.
Red Russian: Flat, fringed leaves with purple stems. It sweetens after frost.
Lacinato (Dinosaur): Dark blue-green leaves with a bumpy texture. It is heat-tolerant and cold-hardy.
Scarlet: A red-stemmed variety that is ornamental and edible. It handles cold well.
Siberian: A hardy type that thrives in cold climates. It is great for fall planting.

Mix different varieties for color, texture, and extended harvest. Some kale varieties mature in 50 to 60 days, while others take 70 to 80 days. Check the seed packet for specific timing.

Common Mistakes When Planting Kale In Minnesota

Even experienced gardeners make mistakes with timing. Here are the most common errors and how to avoid them:

Planting too late in spring: Kale needs cool weather to grow well. If you plant in late May, the heat of June can stress the plants.
Planting too early in fall: If you plant fall kale in September, it may not have time to mature before hard frosts arrive.
Overcrowding: Kale needs space for air circulation. Crowded plants are more prone to disease and pests.
Neglecting to water: Kale needs consistent moisture, especially during dry spells. Inconsistent watering can make leaves tough.
Forgetting to fertilize: Kale is a heavy feeder. Without regular fertilizer, leaves can become yellow and stunted.

By avoiding these mistakes, you will have a much better chance of a successful harvest. Pay attention to your local weather and adjust your planting dates accordingly.

Frequently Asked Questions

Can I Plant Kale In Minnesota In The Summer?

Yes, but only for a fall crop. Plant kale seeds in late July or early August. Summer heat can make spring-planted kale bitter, but fall kale thrives as temperatures cool.

What Is The Latest I Can Plant Kale In Minnesota?

For a fall harvest, plant kale no later than mid-August in southern Minnesota and late July in northern Minnesota. This gives the plants 6 to 8 weeks to mature before hard frosts.

Does Kale Need Full Sun In Minnesota?

Kale grows best in full sun, but it can tolerate partial shade. In warmer parts of Minnesota, afternoon shade can help prevent bolting and keep leaves tender.

How Do I Know When Kale Is Ready To Harvest?

Harvest kale when the leaves are about the size of your hand, usually 50 to 75 days after planting. Pick outer leaves first and leave the inner ones to grow.

Can Kale Survive Winter In Minnesota?

Yes, kale can survive winter under snow or with protection. It can handle temperatures down to 10°F or lower. With row covers or mulch, you can harvest into December or even January.

Final Tips For Success

Planting kale at the right time is the most important step for a good harvest. Start early in spring for a summer crop, and plant again in midsummer for a fall and winter crop. Use season extension methods to get the most out of your garden.

Kale is one of the most rewarding vegetables to grow in Minnesota. It is nutritious, easy to care for, and tolerates cold better than almost any other crop. With proper timing, you can enjoy fresh kale from your garden for most of the year.

Remember to check your local frost dates and adjust your planting schedule accordingly. Keep an eye on the weather and be ready to protect your plants from unexpected cold snaps. Happy gardening in the North Star State.