Any guide to growing kale will start out by telling you it is a cold weather crop, which tastes best after it has been touched by frost.
While cold weather may be kale’s preference, you can grow it during any season and in most climates. The flavor, output and duration from seed to harvest will change depending on the temperature, weather patterns, variety and soil condition, but kale is a hardy crop that is willing to adapt to our expanding desire for it.
With that said, it can tolerate temperatures as low as 20F degrees, but will start to turn bitter and become tough in temperatures over 80F degrees.
If you plan to plant from seed, you may need up to six weeks before your seedlings are ready to plant.
So… let’s get growing!
Different varieties of kale
There are many varieties of kale, but they are usually grouped by the type of leaf:
• Curly leaved (Scots Kale)
• Plain leaved
• Rape Kale
• Leaf and spear (a hybrid of curly leaved and plain leaved Kale)
• Cavolo nero (also known as black cabbage, Tuscan Cabbage, Tuscan (or Toscano) Kale, Lacinato and dinosaur Kale)
In these leaf shapes you’ll find a number of varieties with varied growth time from transplanting to harvesting:
- Blue Armor (45-75 days, hybrid)*
- Blue Curled Scotch (65 days)
- Blue Knight (55 days, hybrid)
- Dwarf Blue Curled (55 days)
- Dwarf Blue Scotch (55 days)
- Dwarf Green Curled (60 days)
- Dwarf Siberian (65 days)
- Greenpeace (65 days)
- Hanover Late Seedling (68 days)
- Konserva (60 days)
- Red Russian (40-60 days)
- Squire (60 days)
- Verdura (60 days)
- Winterbor (60-65 days, hybrid)
Once you’ve picked the varieties that best suit your taste, it’s time to get planting.
Growing Kale in a Pot
If you don’t have the space to grow kale in the garden, or you want to save yourself the hassle, you can grow it in a pot or other soil-appropriate container. The pot or container must have at least six square inches of space for the plant to grow in. Plant your seeds or starts in the center of the pot, following the same fertilization and depth suggested for garden planting (a good layer of compost, with seeds planted ½ inch deep). Make sure to move kale grown in containers into a partially shaded area when summer arrives.
Planting Kale in Your Garden
Stage One: Finding the right spot and time to plant
Kale is a hardy biennial (it take two years to go to flower and complete its life-cycle), but it is usually grown as an annual.
1. If you’re planting during the cool season, find a spot where your kale will receive full sunshine. If you are planting during the warm season, or in a warmer climate, plant kale in partial shade. Kale enjoys companion plants such as beets, celery, herbs, onions and potatoes, but does not enjoy being planted near beans, strawberries or tomatoes.
2. Kale also prefers loamy, well-drained, moist (but not soggy) soil of average fertility. Surprisingly, it isn’t a fan of soil that is too rich in nitrogen, so it will do best with a pH between 5.5 to 6.8. If your soil is too acid, try adding some wood ash to sweeten it. Light, sandy soils and very heavy clay soils will “negatively”* affect the flavor of kale, but it still has the potential to grow in these environments.
3. Seeds will germinate in cool soil, but they sprout best when the soil temperature is around 70 degrees. If you’re starting them inside, then do so 5-7 weeks before the last expected frost. If you’re direct sowing the seeds outside, do so 2-4 weeks before the last frost and/or anytime at least 10 weeks before the first frost of the next season. No matter when you plant, the soil temperature must be at least 40 degrees or higher for good germination.
*The hotter the weather, the more bitter and tough the kale, but even bitter and tough kale is nutritious and can be made into delicious dishes.
Stage Two: Starting your seeds (Skip to stage 3 if you’re planting from pre-grown starts.)
Sow seeds in small pots filled with a mix of soil and veganic fertilizers/compost. Place the seed at least ½ inch deep. Keep the soil around the seedling evenly moist throughout its growth, but allow the top layer of soil to dry between watering.
You can directly sow seeds in the garden starting 2 to 4 weeks before the last frost date or as soon as the ground can be worked in the springtime.
A note on quantity: If you’re going to be using kale on a regular basis (and why wouldn’t you?) you’ll want to have at least 3-4 plants per household member. It is also always a good idea to plant more seeds or buy more starts than you think you’ll need in case some of them don’t make it.
Stage 3: Preparing the bed and planting
Before planting, distribute a good amount* of vegan organic fertilizer over the area you will be using and work it into the soil. Depending on the potency of the fertilizer you are using, you may want to fertilize then cover the bed and allow it to weather for one to two weeks before planting. If you are using seasoned compost to fertilize, you should be able to simply fertilize then plant the next day. If you’re using a mulch to fertilize you can simply place it around the plants after they are in the ground.
If you are planting from starts (that you started 4-6 weeks ago or purchased), put them in the ground 1-2 weeks before the last expected frost date. But only do this if the starts are big enough to survive the weather (they will have at least four true leaves**and the next two leaves will be beginning to form. The plant will usually be approximately 3-4 inches high by this point.)
The recommended space for planting seedlings is 12 to 15 inches apart in rows 18 inches to 24 inches apart. The space for direct sowing is much closer (if you are direct sowing your kale seeds, plant them ½ inch deep and approximately 3 inches apart and then thin plants to 12 inches apart when they are 4 to 5 inches tall.)
No matter the shape of the stem, set the transplants perpendicular to the ground so they will grow straight up, and place them deep enough to support the plant, but no further than the base of their first leaves. We often plant kale 12 to 15 inches apart and then stagger the rows or plant on a diagonal so we can shrink the space between rows. Experiment with what works best in your garden.
*A good amount of fertilizer depends on the type of fertilizer you are using. Follow the directions on the box if you’re using a veganic fertilizer mix. With compost and mulches, you usually want to go a couple of inches deep, while other amendments like seaweed powder or rock dust only require a good sprinkle.
**When a seed first emerges from the soil it has a set of two leaves called cotyledons. These are part of the seed and are its first food source. As the seedling grows, it forms two more leaves which look very different from the cotyledons. These are the first “true leaves” which look more like the plant’s adult leaves, but obviously smaller. Once the true leaves emerge, the cotyledons become unnecessary and eventually wither and fall off.
Stage 4: Care
– Keep your plants well watered. Along with cool temperatures, kale also enjoys moist soil. Keeping the soil most will also help keep the leaves sweet and crisp.
– Side dressing (fertilizing along the rows) with compost throughout the growing season will help keep your kale producing. You can do this approximately every 6-8 weeks.
– If you’re having issues with dirt sticking to and rotting your kale leaves, you can put mulch (such as straw or grass) around the kale once it is at least six inches high.
Insects and diseases that affect kale
Cutworms, cabbage loopers and cabbageworms enjoy munching on kale, but kale is relatively good at resisting disease. Giving your plants the nutrients they need and picking off any withered leaves will help reduce insects found in your garden.
How to Harvest Kale
Kale is usually ready for harvest 70-95 days from seed and 55-75 days from transplanting, depending on the variety you are planting. Check the seed packet for specific times.
– You can begin to cut individual leaves off the kale when the plant is approximately 8 to 10 inches high, starting with the outside leaves first.
– If you decide to harvest the entire plant, cut the stock two inches above the soil and the plant will sprout new leaves in 1 to 2 weeks.
– Make sure to harvest kale leaves before they become too old and tough. If you can’t eat the kale leaves fast enough and they begin to turn brown, pull the old leaves off, and compost them, to free the plants of insect attractants and unnecessary energy drains.
– You can also pick kale regularly and store it in the fridge for up to a week. If you choose to do so, keep it lightly moist and place it in a bag, but unsealed, in the crisper bin.
Second Photo: Flickr (woodlywonderworks)