9 Ways To Keep Your Kale Crop Healthy

The key to a profitable kale crop is ensuring vigorous growth. A properly rooted, irrigated, and fertigated kale planting can regenerate bunchable leaves weekly, providing a harvest for the farmer every seven days for up to three months continuously.

I spoke to farmers and agronomists, who offer a few of their secrets for establishing and maintaining a strong kale harvest. These tips come from farmers growing from between a quarter acre to 40 acres of kale:

1. Select proven varieties for your region. ‘Winterbor’ and ‘Redbor’ (Johnny’s Selected Seeds) are two successful kale varieties that growers recommend. These varieties produce weekly harvests for two to three months. New cultivars are also developed every few years. A recent flat kale variety quickly proving its place in kale production is ‘Mamba’ (Tozer Seeds via Johnny’s). This is a vigorous lactinato-type kale farmers say regrows quickly each week for continuous harvest.
2. Prepare for planting with deep irrigation. Deeply saturate the soil with water in prepared beds prior to planting. First, lay drip tape under a plastic mulch and irrigate through the drip tape for three to six hours or until the soil is thoroughly soaked. Using the drip tape in this way will ensure a slow introduction and absorption of the water into the soil. Once the kale is planted, do not irrigate again for two weeks. This method encourages deep rooting.
3. Fertilize before planting and then weekly once roots are established. Prior to planting, prepare beds by applying pelletized feather meal or another nitrogen- heavy fertilizer. Once the kale is planted and rooted, feeding the plants weekly is essential to the strong and fast regrowth of harvestable leaves. We fertigate with fish emulsion or Chilean nitrate fertilizers. Many conventional farmers use urea or ammonia that is oxidized. Regardless of which type of fertilizer you use, having a weekly routing of feeding is essential to continuous growth.
4. Harvest small leaves early. Most of the initial, first leaves on kale plants are not bunchable. They are small and more delicate than the leaves of mature plants. You can remove these small leaves early to encourage the plant to produce bunchable leaves as the main plant stalk lengthens. Small-scale farmers harvest and bag the small kale leaves into units, making a product that often provides first-to-market early kale sales. Large scale farmers discard the small leaves, removing them to promote further growth of the stalk and future bunchable leaves.
5. Harvest continually for the best regrowth. Kale grows best when it is continually harvested. Harvesting large leaves as soon as they are a bunchable size will encourage faster growth in the younger leaves.
6. Watch for signs of over or under watering.
   To maintain high growth rates, kale needs an irrigation and fertigation plan that responds to weather changes. In general, kale needs 1 to 2 inches of water weekly to grow new leaves. If the weather is cool and cloudy, however, that amount decreases. Overwatered kale, particularly during cool weather when evaporation is minimal, can result in mottled leaves and spots on leaves that can resemble disease. Spots on leaves are typically the first sign of overwatering when the weather is cool. Other initial signs include pale or droopy leaves. If overwatering persists over several weeks, disease often occurs, and nutrient deficiencies can become an issue. However, leaves of most greens, including kale, quickly recover from overwatering if the practice is noted and stopped as soon as possible. Under watering kale is common as well, particularly in hotter months or in hot or dry climates. If a kale crop is underperforming, and if regrowth is slow, chances are a crop is being under watered. Additional signs of underwatering include pale, drooping, or yellowing leaves.
7. Protect kale from cabbage loopers, cut worms, harlequin bugs, flea beetles, and aphids. You can protect kale from most of these pests by covering your crops with a hooped row cover. If your crops aren’t covered, spray insecticides regularly, whether they are organic or conventional, to protect from loopers, flea beetles, and other pests. Aphids thrive on crops that are under a row cover. Treat them proactively by uncovering the plants weekly for several hours and spraying them with neem oil. Neem oil should only be sprayed once the sun has set and there is minimal direct sunlight on crops. Uncovering crops before a soaking rain also will help to reduce aphids. A heavy rain will wash the aphids from the plants.
8. Plant Successions. Most growers plant two successions of bunching kale annually, but some growers have found that planting even three successions of bunching kale works. Exact planting dates depend on location and climates. Tools like row cover can protect kale from frosts and freezing temperatures. Shade cloth can encourage growth into the hotter months. Kale plants stay truly vigorous for two months to three months.
9. Share your tips for growing kale at #kale, #kalefarmer, and #growkale.