- Author: Jane Callier
The Field Test committee of the UC Master Gardeners of Napa county will grow three varieties of kale as their winter crop. Start seed indoors, or sow directly in the ground at the end of July or in August. Refer to the UC Master Gardeners of Napa County website link Vegetable Planting Guide and follow the recommendations for growing cabbage. Most kales are extremely winter hardy, becoming sweeter when kissed by frost. Kale can grow in soils of poorer quality, but avoid planting your kale in areas with potentially high nitrogen that can produce soft leaves that are more susceptible to pest attacks. Kale thrives in well-dug, humus-rich soil with neutral to slightly acidic pH. Cold weather slows insect damage, but also slows the action of soil microbes, so adding a complete organic fertilizer and some bone meal to your beds when you plant winter crops will give the microbes a boost. Give it a sunny spot with well-draining soil and it will truly shine.
Why It's Good for You:
With its deep green leaves and sturdy stalks, kale is loaded with a compound called xeathanthin, which has been shown to help prevent age-related loss of vision. It is a source of calcium and is rich in beta carotene, Vitamin K, lutein, calcium, and potassium. A serving size of 3 ½ ounces of kale provides more Vitamin A than any other green, with the exception of dandelion greens; 120 mgs of Vitamin C with the next closest being arugula at 91 mgs; and 6.6 grams of fiber
Harvesting Tips:
Harvest young leaves from the bottom up, working up the stalk and leaving the new foliage at the top. This way you can keep harvesting for months from the same plants. Avoid picking the inner leaves which protect the growing point.
Pest Management
The cool weather should deter infestations, but be alert and use insecticidal soap for the aphids, or hand pick those worms that refuse to give it up for the winter.
Following is a list of other common pests and diseases that may affect your kale in California. For more information follow the link provided to the University of California Integrated Pest Management website.
In the early 19th century, the Phylloxera aphid wiped out the grape production throughout Western Europe. Aphids are extremely prolific, producing upwards of 20 generations in one season. They live in dense populations, and when living situations become too stressed they can flee by growing wings…
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Cabbage looper
Much like the cabbageworm, loopers are responsible for chewing irregular holes in the leaves of plants. They move by arching their backs as they crawl, and are distinguishable from the cabbageworm by their distinct looping locomotion…
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Cabbage maggot
Below the soil, they tunnel through plant roots, creating passageways for pathogens. These maggots are transmitters of bacterial soft spot and black leg…
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Diamondback moth
The larvae prefer to feed on plants in the Brassica family, and on rare occasions cause serious damage. The introduction of natural predators, such as the parasitic wasp, can easily keep them under control…
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Flea beetle
This leaf-jumper is double-trouble. The adults mainly feed on foliage while the larvae feed on stems and roots of tubers, exposing the plant to fungal infection.
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Harlequin Bug
A member of the stinkbug family, the Harlequin bug doesn't clown around. It efficiently destroys crops by sucking fluids from the plant's tissue…
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Imported cabbage worm
Within a few days of sighting the mature white cabbage butterfly, you can expect to see damage from the hatched larvae. They chew irregular holes in foliage, leaving behind fecal matter…
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Spidermites
These tiny arachnids can be hard to detect, and may go not even be noticed until they have left! They are a common pest to a wide range of vegetables and fruits, but have a taste for sugar peas. They suck the liquid out of plant foliage, and often leave yellowing at the feeding site. Most of the time plants will recover once the mites have left…
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Thrips
Commonly found in gardens and on farms, thrips are a blessing and a burden. While their feeding can cause some scarring to leaves, flowers and fruit surfaces, the effect on overall crop yield is insignificant. Some varieties play a beneficial predatory role by feeding on other insects…
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Weevil
It can be difficult to pinpoint the vegetable weevil as both the adults and larvae are largely active at night. They do not fly, preventing damage from occurring rapidly…
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UC Master Gardeners of Napa County provide free home gardening advice. Visit, call or complete the Plant Problem Diagnosis Sheet for assistance.
Monday, Wednesday and Friday, 9 a.m. to 12 p.m.
UC Cooperative Extension
1710 Soscol Avenue, Suite 4, Napa
(707) 253-4143
http://ucanr.edu/sites/ucmgnapa/
http://www.goodlifegarden.ucdavis.edu/crops/id/24
Rebecca Goodsell, Sonoma County Master Gardener
Denise Seghesio Levine, UC Master Gardener of Napa County