In the past few years, the word “kale” has become synonymous with health, and not without good reason. This nutrient-packed member of the cabbage family is rich in vitamins and minerals and tastes good to boot! As if that weren’t enough to make you want to fill your garden with this tasty plant, most types of kale are also relatively easy to grow thanks to their ability to withstand cooler temperatures. Like many other hearty greens, the leaves’ flavor will actually improve if exposed to cooler temperatures, so light frosts are your friend instead of foe. There are many different varieties of kale, but almost all types are either purple or green in color with broad or curly leaves.
Now there are definitely a few varieties of kale that can be considered jaw droppers (ever heard of Walking Stick kale?) but if there had to be a winner-takes-all, we’d put our money on Redbor kale. This varietal is completely purple in color and can grow up to 5′ in height in regions with long growing seasons! The leaves of this plant are as beautiful inside as they are out and have a sweet, rich flavor that’ll spruce up any salad, especially when the leaves have been exposed to some cool weather.
Seed Depth: 1/4″
Space Between Plants: 2″, thin to 12–18″
Space Between Rows: 18–24″
Germination Soil Temperature: 45–90°F
Days for Germination: 7–14
Sow Indoors: 4–6 weeks before the average last frost, if starting a fall crop start 4–6 weeks before the first fall frost.
Sow Outdoors: 1–2 weeks before average last frost for a late spring/summer crop. For a fall crop, sow seeds in mid to late summer. You can also do successive sowing, starting in early spring and continuing every three weeks.
Vegetative: Not recommended, but can be vegetatively propagated by root or stem tip cutting.
Can be planted either in the spring just prior to the last frost or in the fall, leaving approximately 6 to 8 weeks before the first average frost for the plants to grow. In USDA Zones 8 and warmer, it can continue to be planted throughout the duration of the fall for harvest in the winter. Although plants will be richer in flavor when they are allowed to grow in cooler weather, they are tolerant of most climates.
Natural: Full sun. Will tolerate partial shade but with the trade-off of a lower yield.
Artificial: Although starts or seeds will sprout under most types of indoor lighting, kale responds particularly well to LED and fluorescent lights as they produce less heat than other sources.
Soil: Prefers a loamy, fertile soil with good drainage. A pH of a 5.5 to 7.0 will keep plants healthy and nourished, but a pH of 5.5 to 6.8 is ideal. If your soil has large amounts of clay or sand, try mixing in a soilless potting mix.
Soilless: Unlike other leafy greens, kale does not require a ton of nitrogen, so most standard potting mixes will suffice for getting your greens to grow.
Hydorponics: Does particularly well in hydroponic systems such as NFT or rock wool and can usually be harvested within a month after starting.
Aeroponics: Will thrive in aeroponic systems.
Water: Requires moderate to high levels of water. Aim for 1 to 1.5″ per week but do not allow soil to get soggy as kale is susceptible to root rot.
Nutrients: Unlike other leafy greens, kale is not particularly greedy for nitrogen, so applying a balanced fertilizer or organic compost when first planting outdoors and once or twice throughout the growing season should suffice.
Foliar: Is particularly fond of fish emulsion and liquid seaweed foliar. Apply every 3 to 4 weeks for optimal growth.
Pruning: Although not required, if you are not consistently harvesting your kale, remove older leaves near the bottom of the plant to encourage new growth from the center of the plant.
Mulching: Apply a layer of organic mulch such as straw or wood chips in the late fall to help plants overwinter. Mulch can also be applied in the warmer months to help regulate temperature, but be aware that in heavy rainfall, mulch can trap the water and cause the plants roots to become soggy.
Deficiency(s): Phosphorus, potassium, and calcium are all common deficiencies you may run into. Tilling the soil before sowing or transplanting with an organic compost will help keep the soil fertile.
Rotation: Avoid rotating kale with other members of the cabbage family as they tend to be susceptible to the same diseases.
Companions: Grows well with lettuce, onions, lettuce, chard, carrots, beets, and most herbs. Avoid planting with pole beans, tomatoes, bush beans, and strawberries.
Harvest: Can be harvested when leaves are about 5″ in length, around a month and a half after planting. Pull downward on leaves as close to the main stalk as possible as any pieces of stem that are left over will continue to draw nutrients from the plant. Continue to harvest throughout the season, avoiding taking more than 1/3 of the plant at a time.
Storage: Leaves can be stored in a plastic bag in the refrigerator for up to a week.
Helpful Hint: There are actually two different types of kale available to gardeners—edible and ornamental—so be sure you know the difference between the two varieties before you start snatching up seeds! Ornamental kales tend to grow lower to the ground and usually (thought not always) have leaves that are light at the base and darker around the edges. While these plants are beautiful, they don’t taste nearly as good as the other traditional garden varieties. Redbor kale is often mistaken as an ornamental because it’s so lovely, but it is, in fact, an edible variety. So don’t be fooled if you see it listed as an ornamental plant in your seed catalog!
Preserve: Leaves may be blanched and frozen for 8 to 12 months for optimum flavor. Kale may also be dehydrated and crushed up into a powder which can then be used in smoothies, stews, and soups.
Prepare: This plant has quite tough leaves so they will need to be de-spined and massaged before eating if you are planning on consuming them raw. To prepare, simply cut the leaves away from the center stem and chop into smaller pieces. Add some oil (or our favorite, avocado!) and massage into the leaves. Let sit for twenty minutes to a half hour and enjoy. Leaves may also be cut from the stem, chopped, and added into soups and stews. May also be steamed and stir fried. Try baking in the oven on low temperatures to make kale chips!
Nutritional: This plant has been referred to as a “super food” and with good reason. It is packed with vitamin(s) A, K, C, copper, iron, manganese, phosphorous, potassium, protein, and fiber.
Medicinal: Has been linked in some studies to lowering cholesterol levels. Like other members of the brassica family, kale has also been cited as a means to prevent certain types of cancers including prostate, breast, colon, ovary, and bladder.