Can You Plant Kale in the Winter? - Plant Care Guide

Yes, you can absolutely plant kale in the winter, especially in regions with mild winters (USDA Zones 7 and warmer) or with the aid of protective measures like cold frames or row covers in colder climates. Kale is a remarkably cold-hardy brassica that actually prefers cooler temperatures, and its flavor often sweetens significantly after a few frosts. Winter planting and harvesting allow for fresh greens even when most other garden plants are dormant.

Why is kale an ideal choice for winter gardening?

Kale is an ideal choice for winter gardening primarily because of its exceptional cold hardiness and the unique improvement in flavor that cooler temperatures bring. Unlike many other vegetables that succumb to frost, kale thrives when the weather turns chilly, making it a staple for extending the harvest season.

Here's why kale stands out as a winter garden champion:

1. Exceptional Cold Hardiness:

   • Frost Tolerance: Kale plants can tolerate light to moderate frosts and even temperatures dropping into the teens Fahrenheit (-12°C to -7°C), sometimes even lower for established, mature plants of specific varieties. They are one of the most cold-tolerant vegetables.
   • Survival: While the outer leaves might get a bit tattered in extreme cold, the inner growing points are often protected, allowing the plant to continue producing leaves or recover when temperatures rise slightly.

2. Improved Flavor After Frost:

   • Sweetening: This is one of kale's most celebrated winter attributes. Exposure to cold temperatures triggers the plant to convert starches into sugars as a natural antifreeze mechanism. This results in kale leaves that are noticeably sweeter, less bitter, and more tender than those harvested in warmer weather. This phenomenon is called "frost sweetening."

3. Long Harvest Window:

   • With proper planting (often in late summer/early fall for winter harvest), kale can provide a continuous supply of fresh greens for many months, often from fall right through to spring, long after delicate crops have withered.

4. Nutrient Density:

   • Kale is a nutritional powerhouse, packed with vitamins A, C, and K, as well as calcium and antioxidants. Having access to these fresh nutrients during winter, when other fresh produce might be less available, is a significant benefit.

5. Easy to Grow:

   • Kale is a relatively low-maintenance crop, tolerant of a range of soil types (though it prefers well-drained, fertile soil) and less prone to bolting (going to seed) in cool weather compared to other leafy greens like lettuce.

6. Pest Reduction:

   • Many common kale pests (like cabbage worms, aphids, and flea beetles) are less active or go dormant in colder temperatures, reducing the need for pest control during winter.

7. Container Versatility:

   • Its cold hardiness also makes it suitable for growing in containers, which can then be moved to protected locations (like porches or unheated garages) during severe cold snaps.

In summary, kale's ability to not just survive but actually improve in flavor with cold makes it an exceptional choice for extending the gardening season and enjoying fresh, nutritious greens throughout the winter months.

What are the best kale varieties for winter growing?

Choosing the best kale varieties for winter growing means selecting those specifically known for their exceptional cold hardiness and improved flavor after frost. While most kales are cold-tolerant, some stand out for their resilience in chilly temperatures and enhanced sweetness.

Here are some of the top kale varieties for winter gardening:

1. 'Lacinato' Kale (also known as Dinosaur Kale, Tuscan Kale, or Cavolo Nero):

   • Appearance: Distinctive, dark blue-green, deeply savoyed (bumpy) leaves with a somewhat crinkly texture.
   • Cold Hardiness: Very cold-hardy, often tolerating temperatures into the teens Fahrenheit (-10°C to -7°C).
   • Flavor: Renowned for its tender texture and sweet, earthy flavor that significantly improves after frost. Excellent for sautéing, soups, and kale chips.
   • Why it's great for winter: Its dark color absorbs more solar radiation, and its robust leaves hold up well to cold. You can find Lacinato kale seeds for easy planting.

2. 'Red Russian' Kale:

   • Appearance: Flat, frilly, deeply lobed leaves with a beautiful purple-red tint on the stems and veins, deepening in cold weather.
   • Cold Hardiness: Extremely cold-hardy, often surviving down to 10°F (-12°C).
   • Flavor: Very tender leaves with a mild, sweet flavor. Another variety that sweetens noticeably after frost.
   • Why it's great for winter: Its hardiness and attractive coloration make it a garden standout in winter.

3. 'Winterbor' Kale (Hybrid):

   • Appearance: Very curly, dark green, intensely ruffled leaves.
   • Cold Hardiness: Bred for excellent cold tolerance, often considered one of the most robust varieties for severe winters. Can tolerate single-digit temperatures with protection.
   • Flavor: Good, slightly peppery flavor that also sweetens.
   • Why it's great for winter: Its vigorous growth and exceptional hardiness make it a reliable choice for cold climates.

4. 'Siberian' Kale:

   • Appearance: Large, broad, slightly ruffled green leaves.
   • Cold Hardiness: True to its name, 'Siberian' kale is one of the most cold-tolerant varieties available, handling frigid temperatures remarkably well.
   • Flavor: Mild and tender, and it sweetens well in the cold.

5. 'Redbor' Kale (Ornamental and Edible):

   • Appearance: Striking, intensely ruffled leaves that are a deep purple-red, becoming more vibrant in cold weather. Often grown as an ornamental.
   • Cold Hardiness: Good cold tolerance, enhancing its color and flavor.
   • Flavor: Edible, with a similar taste profile to other kales, benefiting from frost.

Table: Top Kale Varieties for Winter Growing

When selecting seeds, look for descriptions that emphasize "cold-hardy" or "winter-tolerant" to ensure the best performance in your specific climate.

What is the ideal planting time for kale to harvest in winter?

The ideal planting time for kale to harvest in winter is typically in late summer to early fall, about 8-10 weeks before your first anticipated hard frost date. This timing allows the kale plants to become well-established and develop to a good size before the colder temperatures of deep winter arrive, ensuring a robust and continuous harvest.

Here’s a breakdown of considerations for ideal planting time:

1. For Mild Winter Climates (USDA Zones 7 and warmer):

   • Planting Window: You can often plant kale from late August through October (and sometimes even into November/December in very mild, frost-free zones like Florida or Southern California).
   • Goal: The plants will grow actively through fall, providing harvests in late fall and throughout the winter. In these climates, kale might continue to grow slowly all winter.

2. For Cold Winter Climates (USDA Zones 6 and colder, with protection):

   • Planting Window: It's best to plant kale seeds or seedlings in late July to early September.
   • Goal: The plants need enough time to reach a decent size (at least 6-8 true leaves) and establish a strong root system before hard frosts and freezing ground temperatures set in. This makes them more resilient to the cold.
   • Protection is Key: These plants will then need protection (cold frame, row cover, hoop house) as winter approaches to survive the harshest temperatures and allow for harvesting.

Key Considerations for Timing:

• Days to Maturity (DTM): Check the DTM on your seed packet. This tells you how long it takes from planting to harvest. For winter, you want the plant to be near or at maturity before the coldest weather.
• Establishment Before Hard Freeze: A robust, well-established plant is much more cold-hardy than a small seedling. Aim for at least 6-8 weeks of good growth before temperatures consistently drop below freezing.
• Succession Planting: For a continuous supply, you can sow small batches of kale seeds every 2-3 weeks during your fall planting window.
• Seedling vs. Direct Sow:
  • Direct Sowing: Easier, but takes longer for plants to reach harvest size. Ensure soil is warm enough for germination (above 45°F / 7°C).
  • Transplants: Starting seeds indoors 4-6 weeks before your target outdoor planting date, then transplanting seedlings, gives you a head start and a more reliable crop. This is often preferred in colder zones or if you want larger plants faster. You can find kale seeds to start.

By carefully timing your planting, you can ensure your kale plants are robust enough to withstand winter conditions and provide a continuous harvest of sweet, flavorful greens.

What protective measures are needed for winter kale?

While kale is exceptionally cold-hardy, implementing protective measures can significantly extend your harvest season, protect plants during extreme cold snaps, and allow for winter kale growing even in colder climates. These measures create a microclimate that shields plants from the harshest elements.

Here are essential protective measures for winter kale:

1. Mulching:

   • Method: Apply a thick layer (4-6 inches) of organic mulch around the base of your kale plants. Use straw, shredded leaves, aged wood chips, or pine needles.
   • Benefit: Mulch insulates the soil, helping to regulate soil temperature and prevent extreme freezing and thawing cycles. It also helps retain moisture, which is crucial for root health. It primarily protects the roots and crown of the plant.

2. Row Covers / Floating Row Covers:

   • Method: Use lightweight floating row covers directly over your kale plants. These spun-bonded fabrics allow light and water through but trap heat. For more warmth, use a heavier weight fabric.
   • Benefit: Provides a few degrees of frost protection, helps retain warmth from the soil, and can protect against cold winds. It also keeps out some winter pests.
   • Application: Drape directly over plants or support with hoops for more space. Secure the edges with soil or weights to prevent wind from blowing them off.

3. Cold Frames:

   • Method: A cold frame is a bottomless box with a transparent lid (glass or clear plastic) that traps solar heat. Place it over your kale plants.
   • Benefit: Offers significant protection, raising temperatures inside by 10-20°F (5-11°C) higher than ambient air. Excellent for extending the season in colder zones.
   • Ventilation: On sunny, mild winter days, vent the cold frame by propping open the lid to prevent overheating, which can cook your plants. Close it again before sunset.

4. Hoop Houses / Low Tunnels:

   • Method: Similar to cold frames but larger. Create hoops (from PVC pipe or metal conduit) over your garden bed and cover them with greenhouse plastic or a heavy-duty row cover.
   • Benefit: Provides excellent protection for larger sections of a garden, creating a mini-greenhouse effect.
   • Ventilation: Also requires ventilation on sunny days to prevent overheating.

5. Watering Before a Freeze:

   • Method: Water your kale thoroughly a day or two before an anticipated hard freeze.
   • Benefit: Moist soil retains heat better than dry soil, releasing it slowly overnight and helping to keep plant roots warmer. The water within plant cells also helps prevent ice crystal formation.

6. Container Gardening & Moving Indoors:

   • Method: Plant kale in containers, which can be moved to a protected location (unheated garage, porch, sunroom) during severe cold snaps or during the coldest weeks of winter.
   • Benefit: Offers maximum flexibility and protection.

By combining these protective measures, you can dramatically increase the chances of a successful and continuous winter kale harvest, even when the weather outside is truly frightful.

How do you harvest kale in winter without damaging the plant?

Harvesting kale in winter without damaging the plant is key to ensuring a continuous supply of fresh greens for many months. The technique focuses on taking individual leaves while preserving the plant's central growing point, allowing it to regenerate.

Here's how to harvest kale in winter:

1. Choose the Right Leaves:

   • Outer, Mature Leaves: Always harvest the outer, most mature leaves first. These are the larger leaves around the base of the plant.
   • Avoid Central Growing Point: Crucially, do not harvest the very top, central cluster of young leaves from the plant's crown. This is the plant's primary growing point, and damaging it will halt future production.

2. Technique for Removing Leaves:

   • Snap or Cut: You can either:
     • Snap: Firmly bend an outer leaf stem downwards and outwards until it snaps cleanly from the main stalk.
     • Cut: Use clean, sharp pruning shears or a knife to cut the leaf stem close to the main stalk, taking care not to nick the stalk itself or any nearby smaller leaves.
   • Clean Break: Aim for a clean break or cut to minimize damage and prevent entry points for disease.

3. Leave Enough Foliage:

   • Minimum 4-6 Leaves: Always leave at least 4-6 inner, smaller leaves on the plant after harvesting. These leaves are essential for the plant to continue photosynthesis and gather energy for new growth. Stripping the plant bare will weaken or kill it.

4. Harvesting Frequency:

   • "Cut and Come Again": Kale is a "cut and come again" crop. Harvest as needed, typically a few leaves from each plant every week or two, depending on growth rate.
   • Slow Growth in Deep Winter: In the coldest periods of winter, kale growth will slow significantly, so harvests will be less frequent and smaller. Respect the plant's slower pace.

5. Timing of Winter Harvest (Relative to Hard Freezes):

   • Before a Deep Freeze: If a very hard, prolonged freeze is predicted (e.g., temperatures consistently below 10°F / -12°C for multiple days), consider harvesting a larger quantity of leaves before the freeze. The plant's overall growth might be set back by extreme cold, and harvested leaves can be stored.
   • After a Light Frost: The best time to harvest for peak sweetness is after a light to moderate frost, as this is when the sugars are concentrated.

6. Inspect for Damage:

   • After harvesting, quickly check for any yellowed, heavily damaged, or diseased leaves. Remove these as well to maintain plant health.

By following these gentle harvesting techniques, you can enjoy the delicious, frost-sweetened benefits of your winter kale patch for an extended season, ensuring the plants remain productive for many months.

How do you prepare your garden bed for winter kale planting?

Preparing your garden bed for winter kale planting is a critical step that lays the foundation for healthy, resilient plants able to withstand colder temperatures and produce a bountiful harvest. The focus is on providing rich, well-draining soil and a protected environment.

Here’s how to prepare your garden bed for winter kale:

1. Choose the Right Location:

   • Full Sun: Kale, even in winter, needs full sun (at least 6-8 hours of direct sunlight daily). While sun is weaker in winter, it's still essential. Choose a spot that gets maximum winter sun exposure.
   • Shelter: If possible, select a location that offers some natural shelter from harsh winter winds, such as near a wall, fence, or evergreen hedge.

2. Clear the Bed:

   • Remove Old Plants/Debris: Clear out any spent summer crops, weeds, or plant debris. This prevents competition for nutrients and reduces potential overwintering sites for pests and diseases.
   • Weeds: Remove all weeds, as they will compete with your kale.

3. Amend the Soil for Fertility and Drainage:

   • Rich in Organic Matter: Kale is a relatively heavy feeder and thrives in fertile, well-draining soil. Dig in a generous amount (2-4 inches) of well-rotted organic compost or aged manure. This provides slow-release nutrients, improves soil structure, and enhances moisture retention.
   • Drainage: Ensure the soil drains well. Kale does not like "wet feet," especially in cold weather, as soggy roots can lead to rot. If you have heavy clay, amend with extra compost or grit.
   • pH Level: Kale prefers a slightly acidic to neutral soil pH, ideally between 6.0 and 7.0. A soil pH test kit can confirm your soil's pH.

4. Loosen the Soil:

   • Dig or lightly till the bed to a depth of at least 8-12 inches. This improves aeration and makes it easier for kale roots to establish. Break up any large clumps of soil.

5. Incorporate Balanced Fertilizer (Optional, based on soil test):

   • If your soil test indicates a nutrient deficiency, you can incorporate a balanced granular fertilizer (e.g., 5-10-10 or 10-10-10 NPK) at the rate recommended on the package. Avoid excessive nitrogen, which can lead to lush growth that is more vulnerable to cold.

6. Level and Refine:

   • Rake the soil surface smooth and remove any remaining rocks or debris to create an even planting bed.

7. Consider Raised Beds or Containers:

   • Raised Beds: If your native soil is poor or drainage is an issue, a raised garden bed filled with a custom mix (compost, topsoil, perlite) is an excellent option. Raised beds warm faster in spring and drain better.
   • Containers: For maximum flexibility to move plants for protection, large garden containers with well-draining potting mix are suitable.

8. Plan for Protection:

   • Think about your winter protection strategy (cold frame, row covers, etc.) before planting. You might need to install hoops or structures for row covers at the same time you plant.

By dedicating time to proper bed preparation, you create a robust and nourishing environment that allows your kale plants to not only survive but thrive throughout the winter months, producing delicious, frost-sweetened leaves.

What watering and feeding do winter kale plants need?

Watering and feeding winter kale plants requires a nuanced approach, as their needs shift with the colder temperatures and slower growth rates. The goal is to provide consistent moisture without waterlogging and gentle feeding to sustain production without encouraging tender new growth.

Watering Winter Kale:

1. Reduce Frequency:

   • As temperatures drop and daylight hours shorten, kale's water needs decrease significantly. The soil also dries out much slower in cool weather.
   • Water less frequently than you would in summer.
   • Check Soil Moisture: Always check the soil moisture first. Stick your finger 1-2 inches deep; if it feels damp, wait. Only water when the top few inches of soil feel dry.
   • A soil moisture meter for winter gardening can be very helpful.

2. Water Deeply When You Do:

   • When you do water, water deeply to encourage deep root growth.
   • Avoid Overhead Watering: Water at the base of the plant to keep foliage dry, especially when temperatures are cold or humidity is high. Wet leaves in cold weather can promote fungal diseases.
   • Morning Watering: If watering is needed, do it in the morning so that any moisture on leaves has time to dry before nightfall.

3. Water Before a Freeze:

   • As mentioned in protective measures, watering thoroughly a day or two before an anticipated hard freeze helps insulate the soil and roots.

4. Container Kale:

   • Kale in containers will still dry out faster than in-ground plants, so they will need more frequent watering, but still less than summer. Always check moisture before watering.

Feeding Winter Kale:

1. Initial Soil Enrichment is Key:

   • If you prepared your garden bed well with ample organic compost or a slow-release granular fertilizer before planting, your kale might need very little additional feeding through the winter. This initial enrichment is crucial.

2. Light, Balanced Feeding (Optional Mid-Winter Boost):

   • During active growth in fall, or if harvesting regularly through a mild winter, you might consider a very light, diluted feed every 4-6 weeks.
   • Use a balanced liquid fertilizer (e.g., 5-5-5 or 10-10-10 NPK) at half or quarter strength.
   • Avoid High Nitrogen: Do not use high-nitrogen fertilizers in winter, as they will stimulate tender new growth that is highly vulnerable to frost damage. The goal is to sustain the existing plant, not force rapid new growth.

3. Listen to Your Plants:

   • If your kale plants are still producing well and look healthy and green, they likely don't need more fertilizer.
   • If they start to look pale, yellow (and other issues like overwatering have been ruled out), or growth slows dramatically beyond what's expected for cold weather, a light feed might help.

4. Stop Feeding in Deep Winter/Hard Freeze:

   • When temperatures are consistently very cold and the plants are growing extremely slowly or are protected under covers, cease fertilization. The plant is essentially dormant or growing minimally and won't efficiently use the nutrients. Resume only when temperatures consistently rise in early spring.

By adjusting your watering and feeding to the slower, colder pace of winter, you can successfully maintain a healthy and productive kale patch, ensuring fresh, sweet greens even in the chilliest months.