How to Plant, Grow, and Care for ‘January King’ Cabbage
‘January King’ is an exceptional cabbage with impressive cold-hardiness and beautiful color. In this article, vegetable farmer Briana Yablonski will share tips and tricks for caring for these plants.

Contents
Although many hybrid cabbage varieties exist, growers still love the heirloom January King. This variety has impressive cold tolerance, beautiful color, and great flavor.
If you want to grow this cabbage in your garden, you should be aware of its long maturity time and common pests and diseases. I’ll explain how to start them from seed, provide the proper growing environment, and keep your ‘January King’ cabbages happy until they’re ready to harvest.
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Brassica oleracea ‘January King’ Cabbage Overview

Plant Type
Vegetative annual
Family
Brassica
Genus
Brassicaceae
Species
Oleracea var. sabauda
|
Native Area
Europe
Exposure
Full sun
Height
6-12 inches
Watering Requirements
Moderate
|
Pests & Diseases
Flea beetles, cabbage worms, harlequin bugs, black rot, alternaria leaf spot
Maintenance
Low
Soil Type
Rich and well-draining
Hardiness Zone
3-9
|
What Is It?

While some cultivar names leave us guessing, the meaning behind ‘January King’ is straightforward. This impressively cold-hardy cabbage stands out in barren winter fields when other veggies and ornamentals have succumbed to the cold. The purple-tinged heads remain crisp and delicious even when temperatures dip to 5°F (-15°C).
Gardeners have been growing this heirloom variety for over 100 years. Although seed breeders introduced many hybrid cabbages during this time, ‘January King’ remains a favorite among many growers.
Characteristics

‘January King’ is a slow-growing cabbage described as a cross between a white and savoy cabbage. The plants have wrinkled leaves similar to those of most savoy varieties, but the outer leaves resemble those of white cabbage. When the slightly flat heads are mature, they weigh between three and five pounds and have purple-tinged outer leaves.
Although this cabbage is cold-tolerant, it matures slowly. Depending on when and where you plant it, expect it to take 160-210 days to mature.
Native Area

Although the versions of Brassica oleracea we grow in our gardens vary drastically from the wild version, scientists think the original plant is native to Europe. Plant breeders have taken this native plant and bred it to produce modern varieties of cabbage, cauliflower, and kale.
Planting

‘January King’ cabbage grows best outdoors in the ground or in raised beds. Like most cabbages, it’s a cool-weather crop that grows best in spring, fall, and winter. Fall crops are easier to grow (and allow you to utilize the plant’s cold hardiness), but you can also try to produce spring cabbages.
Growing from Seed

Unless you can find ‘January King’ seedlings at a nearby nursery or garden center, plan on growing these brassicas from seed. Fortunately, this is an easy process.
Since this cabbage variety matures in about six months, you should sow the seeds well before you hope to harvest the mature heads. The ideal sowing time depends on your growing zone, but you should plan on starting seeds in January or February and again in June or July. The seedlings will be mature and ready to transplant about a month after you plant the seeds.
Cabbage grows best when transplanted, so plant to sow your seeds indoors. Start with your preferred seed starting trays and a well-draining soil mix designed for seedlings. Fill each tray with moist soil mix, make a quarter-inch hole in each cell, place one to two seeds, and gently cover.
Place the trays somewhere between 75-90°F (24-32°C) and keep the soil moist. If you don’t have a warm area, place the trays on a heat mat to warm the soil. You should see the seedlings emerge within a week.
Once germination occurs, place the seedlings in a cooler environment where the air temperature is between 55-75°F (13-24°C). You should also make sure the little seedlings receive at least ten hours of bright light each day. If you don’t have access to a south-facing window or greenhouse, you can use a grow light to provide supplemental light.
If you planted more than one seed per cell, thin to one plant per cell once the seedlings have a set of true leaves. They should be large enough to be transplanted outdoors in four to six weeks.
Transplanting

Since ‘January King’ cabbages take around six months to mature, you want to make sure you get them in the ground early. That means transplanting in the late winter for spring crops and in the middle of summer for fall crops.
No matter when you transplant, remember to slowly acclimate your seedlings to outdoor light, temperature, and wind before planting them outdoors. Keep the soil moist for the first few weeks after transplanting.
If you’re planting multiple cabbages, space them 18-24” apart. You can plant fast-maturing crops like radishes, spinach, or lettuce between the plants as they grow. This interplanting will help you maximize your garden space while limiting weeds and conserving moisture.
Spring Crops

The seedlings can tolerate a light frost, especially if you cover them with row cover. Therefore, you can plant them outdoors as early as the beginning of February in zones 7-9. If you expect temperatures to dip below 20°F (-7°C), add an extra layer of row cover to protect them from cold damage.
If you live in zone five or below, skipping a spring crop is best. Cold temperatures mean you won’t be able to transplant them outdoors until April or May, and this late planting date means the crops will have to mature in the warmer days of summer. Instead, plant in the summer for a fall harvest.
Fall Crops

Harvesting these cabbages in the late fall or winter allows their cold hardiness to shine. Plus, the cooler weather causes the plants to concentrate their sugars and become delectably sweet.
Aim to transplant your plants about five to six months before you hope to harvest. For example, transplant your seedlings in June or July if you want to pick frost-kissed cabbages in mid-January.
Since cabbages don’t like hot weather, you may need to baby them as they transition to the hot summer weather. Keep the soil moist and watch for pests like aphids, harlequin bugs, and cabbage worms.
How to Grow

‘January King’ is easy to grow as long as you plant the crop at the right time of the year. It’s also important to keep an eye out for pests and diseases.
Light

These brassicas grow best in full sun. That means you should plant them in an area that receives at least ten hours of bright, direct light each day. It’s fine if your plants receive more light, but they may suffer if they receive less.
Water

These cabbages require a moderate amount of water to remain healthy. The exact amount of water to apply varies depending on the soil type, temperature, air moisture, and mulch. However, you should expect to provide your crop with one to two inches of water per week.
Since wet foliage increases the chances that the plants will develop fungal diseases, apply water near the base of the plants. You can irrigate using a watering can, hose, or automated drip irrigation system. No matter which method you use, aim to keep the soil moderately moist.
Soil

‘January King’ cabbages grow best in well-draining soil rich in organic matter. The plants can grow well in clay, loam, and sand if the soil has good aeration, drainage, and proper nutrients.
If you notice your soil is compacted, loosen it before planting. There are multiple methods for aerating, but loosening the soil with a digging fork is an easy solution. Simply insert the tines of the fork into the ground, then pull the handle back until the soil cracks. Repeat this process every ten inches.
Temperature and Humidity

Like most brassicas, this cabbage prefers cooler weather, especially as it matures. That’s one reason fall plantings are often more successful than spring crops.
As mentioned above, this variety is well known for its cold tolerance. Unprotected, it can survive temperatures as low as 5°F (-15°C), and a few layers of row cover help it tolerate subzero temperatures.
The plants prefer low humidity, but they can also tolerate moderate and high humidity. However, higher humidity makes the plants more likely to develop some types of diseases.
Fertilizing

Cabbage plants are heavy feeders that require a large amount of nitrogen to remain healthy. However, you should be careful to apply this nitrogen at the proper time.
Adding a nitrogen-rich fertilizer like feather meal or blood meal during planting will provide the small plants with the nutrients they need to thrive. However, you should avoid applying nitrogen once the plants begin to mature since this can lead to problems with head formation.
These plants also require potassium, phosphorus, and micronutrients to remain healthy. Conducting a soil test is the best way to determine how much of these nutrients to apply. However, if you want to forgo a soil test, apply a balanced granular fertilizer with an NPK ratio of 10-10-10 at planting time.
Harvesting and Storage

Technically, you can harvest and eat cabbages in any state. However, you probably want to wait until the plants form dense heads. Harvesting mature heads allows you to enjoy the tender, crunchy leaves you dreamed of.
The days to maturity can help you determine when your plants are ready to harvest. Start checking the plants about five months after you plant the seedlings in the ground. Mature heads will be firm to the touch.
Harvest by cutting the entire head near the ground. You can easily strip off dirty or damaged leaves to reveal a beautiful cabbage head. However, it’s best to leave exterior leaves on the heads if you plan to store them in your refrigerator or root cellar.
While you can store ‘January King’ cabbage in cool conditions for a few months, remember that these plants also hold well in winter fields. That means you can leave the cabbages in your winter garden and harvest them when you need.
Common Problems

Unfortunately, ‘January King’ cabbage is susceptible to various pests and diseases. Knowing which common problems to look for can help you keep your plants healthy.
Pests

These cabbages are prime targets for many brassica pests. Most of these pests are more common in warmer weather, so keep an eye out for them on maturing spring crops and summer-transplanted seedlings.
Flea Beetles

Flea beetles are a group of tiny, dark beetles that attack a range of vegetative crops. Most flea beetle species are less than a quarter of an inch long and sport long antennae. The pests can’t fly, but they hop when disturbed.
Flea beetles chew tiny holes in cabbage leaves. While a dozen flea beetles aren’t a big problem, these pests often appear in large numbers and shred plant leaves. They can be especially harmful to small seedlings.
One way to control flea beetles is to cover your plants with insect netting or lightweight row cover when planting time. This will exclude the pests from your crops. However, it’s important to note that flea beetles overwinter in the soil. Therefore, your plants may come under attack even if you cover them. If you notice flea beetles on your covered plants, remove the coverings and resort to other control measures.
If you experience a large flea beetle outbreak, you can spray the pests with neem oil, insecticidal soap, or pyrethrins. Make sure to always follow product instructions when applying these products.
Harlequin Bugs

Although these shield-shaped bugs are beautiful shades of red, white, and black, they can seriously damage cabbage plants. Both adults and nymphs feed on cabbage leaves using piercing and sucking mouthparts. This feeding weakens leaves and makes the plants more susceptible to diseases.
You can control harlequin bugs by picking them off the plants. Make sure to remove the adults and nymphs and the round, black and white eggs. Other control measures include neem oil, pyrethrins, and insecticidal soap.
Cabbage Worms

Cabbage worms are a group of caterpillars that feed on brassicas like the ‘January King’ cabbage. Some cabbage worms are small green caterpillars, and the cross-striped cabbage worm is a mix of gray, black, and yellow.
All of the larval forms of these pests feed on cabbage foliage and create irregular holes. Tiny cabbage worms can cause small holes, while larger caterpillars can create ragged leaves with large irregular holes. This damage can kill seedlings and severely damage older plants.
One way to control the pests is to remove the adults and eggs by hand. Check your plants at least twice weekly to keep up with the pests.
You can also spray your plants with Bt. This naturally-occurring bacteria stops the cabbage worms from feeding while leaving other insects unharmed.
Diseases

‘January King’ cabbage is susceptible to numerous diseases, but most of these can be prevented with cultural controls. Treatment is difficult once they take hold of your plant, so do your best to prevent them from occurring.
Black Rot

This bacterial disease impacts brassicas like ‘January King’ cabbage. The first symptoms are yellow leaf edges, which progress into brown or black leaves. The disease can lead to deformed cabbage heads and plant death.
Black rot can enter the garden via infected seeds, so make sure to buy your seeds from a trusted source that verifies seeds have been tested for the disease. Watering at the base of the plant also limits the spread of the disease, as does rotating brassica crops in your garden.
Once plants are infected, there is nothing you can do. The best option is to remove them to prevent the disease from spreading to other plants.
Alternaria Leaf Spot

This fungal disease causes round, brown spots on cabbage leaves. If you look closely, the spots consist of concentric circles. As the disease spreads, you may notice large patches of brown.
Purchasing clean seeds, rotating brassica crops, and removing infected plants from your garden can help prevent alternaria leaf spot. It’s difficult to treat this disease once it appears, so remove infected plants to limit its spread.
Frequently Asked Questions
Can you eat ‘January King’ cabbage raw?
The tender leaves of ‘January King’ cabbage work well raw in sales and salads. You can also cook the cabbage leaves.
Is ‘January King’ cabbage a hybrid?
No. ‘January King’ is an heirloom cabbage with impressive cold tolerance.