Kale is one of my old reliable super crops. You get a bunch of leafy greens and some nutrient dense material to mix into salads, smoothies, or other assorted meals. Kale is now one of my favorite crops and was perpetual and nonstop for me back when I was in zone 7.
This article is about all you need to know to grow kale. You just get the grow conditions right and you can take it all the way from seed to kitchen. I know some tricks to extending the time it can be kept growing as well as some notes on different varieties. With a little care and avoiding pests, you can have a very resilient crop.
So you want to grow kale?
When to Grow Kale
Kale likes to grow in a temperature range that is pretty forgiving and can chug along between 35-75°F. The desired temperature should be in a “cool” range like around 65°F. Kale is a cole crop the same as the other brassicas like broccoli or cabbage, it likes it cold.
In my zone 4 location it has two main growing times in the spring and then later in the fall. Down in zone 7 my winters were warmer and it would often keep growing even with the little frost touches. During times when I thought it might be a bit too much I would use the lightest of plant protection and the kale would survive quite easily. The leaves also had a much more mild or almost sweet flavor after a little frost kiss.
My general observation was the crop could about be perpetual until heat would cause it to “bolt”. Indeed, kale is very flexible with the cold but is not very tolerant to any sort of heat.
In many locations kale can be in the garden all winter as long as the temperatures don’t go below 10°F. You will have a good many months where there are chances to harvest leaves.
Though kale will usually bolt once any amount of heat is present. Once the plant is trying to “bolt” you will see it form flowers and try to produce seeds. The leaves will degrade in quality and the taste will have a bitter bite.
Though kale may also bolt if it survives until spring because of the long daylight hours. Even when cold the longer light periods may trigger the plant to seed.
Planting Kale: Seeds or Starts
Kale can be grown pretty easily by direct sowing seeds. Though I prefer starting indoor seedlings I move outdoors so I can select the best starts. Each growing location has ideal times to plant so you have to determine your hardiness zone from a planting calendar.
You usually want to plant kale seedling outside in late winter to capture the cool weather up to early spring. Ideal should be as early as 3 or 4 weeks before the average last frost date. The seedlings often need some sort of frost cover so a heavy cold snap doesn’t kill them.
Fall harvest requires you to plant kale 6-8 weeks before the first average fall frost date. For many places that is right around later summer. When I lived in zone 7 the plants cruised through winter though their growth was slower.
Kale seeds should be planted into well-draining soil around ¼ inch deep. They need consistent moisture to germinate so many use a planting tray of some kind with a humidity dome. See this guide for more tips on starting and raising seedlings indoors.
Before planting you want to spend time hardening off your sprouts. When it is time to move kale seedlings to their outdoor plant beds they need to be spaced 12 inches apart. You want to bury them up to their first leaf set then water them to “tuck them in”.
But again your options are to start seeds indoors, direct sow seeds outdoors, or source nursery seedlings use those for plant starts. Sometimes I use nursery kale starts so I have more sprouting space for plants I can’t easily buy.
Optimal Kale Growing Location
Kale prefers cool soil that is rich in nutrients and damp. The soil should drain well and not be waterlogged. Kale isn’t a nutritionally demanding plant but it does like the steady supply of compost or other fertilizer like worm castings. I usually amend the soil before planting out my starts.
When growing kale in containers I tend to fertilize lightly from time to time with worm tea. The container needs to drain well.
Kale seems to be pretty forgiving when it comes to sun conditions. I’ve had it grow in full sun as well as had some tucked away in some shady side gardens. Kale plants usually like around 7 hours of sun. If you are doing a spring planting and have hot summers, you might try locations that have shade as it will help slow down when the plant tries to bolt.
There are several general kale varieties and many cultivars to go with. My two favored kale is lacinto kale and red russian kale, though I grow a lot of other types from year to year. You will want to test things out and see what grows particularly well for your garden.
Lacinato or Tuscan Kale – This is an Italian variety of kale. It has long, large, narrow leaves with a bumpy texture. The color is a rich green and blue. A common name for it is “dino kale”. This kale tends to grow pretty tall and is favored for kale chips. I usually buy Tuscan for my garden, though there are a few other cultivars.
Russian Kale – This kale has mostly flat leaves with fringed edges, the shape looks a lot like oak leaf lettuce. Russian kale is probably has the best leaf taste as it is very mild even with large leaves. The usual cultivar I buy for my garden is Red Russian, though you can also choose from Green Russian, or White Russian.
Curly Kale – This kale is very common in grocery stores and features light green leaves best described as being “frilly”. This is the kale you usually think of when you think of kale. They are abundant leaf growers and are really cold-tolerant. Popular cultivars are Vates, Dwarf Blue, or Winterbor among others.
Portuguese Kale – This is another Mediterranean variety that has large flat leaves with thick veins. This variety is known for being more heat-tolerant than the other kale assuming people are familiar with it as it isn’t common in a lot of US garden circles.
Ornamental kale– These are kale generally used for fall or winter landscaping. Some people like to have them around for the good looks though they are also edible for anyone who wants a nibble.
Kale likes moderate watering and prefers damp soil that isn’t dried out. Raised beds generally stay moist for longer periods, especially if mulched. Though I grew my kale in containers this year and they dry out very frequently and need more maintenance in terms of watering.
Fertilizing throughout the season
Before any planting period many gardeners add compost to their garden. From there they may choose a secondary fertilizer that is mild or opt for things like worm tea. I usually plant my seedlings in the garden and do a worm tea watering to help get the roots established.
Extending the Season
In order to grow kale for long stretches of the year you need the best variety for the task. Heat-tolerant varieties like the Portugese kale are slow to bolt when it is warm. Other kale have higher tolerance to frost or can even grow despite snow.
Being they are normally a cold weather crop the usual challenge is getting them through the long cold periods. With minimal frost protection like hoop houses, cloches, or cold frames kale can persist or even survive the winter months depending on your growing zone.
Kale can be harvested for baby greens after 30 days. For more mature leaves you don’t need to wait much longer at around 60 days.
Kale is a nice crop where you should collect leaves pretty often in small amounts. When you harvest it promotes the plant to promote new growth for future harvests. The other problem is old leaves might get tougher instead of tender. You don’t want to strip the plant of all the leaves, you want to collect a little here and there and leave plenty to photosynthesize.
The best way to collect leaves is to cut the old leaves starting from the bottom on the outermost part of the plant. You don’t want to harvest all the leaves but just pluck some from the main stem. You don’t want to harvest leaves in the center of the plant as you will damage the terminal bud. If the terminal bud is damaged then you will stop getting good plant growth.
The harvested leaves last a pretty long time when stored in an air-tight container in the fridge.
Common Kale Pests
Since kale is related to the same family as cabbage, one big pest is cabbage worms. You might also fight aphids, flea beetles or harlequin bugs. You will either see holes, lace leaves, or big fat aphids feeding and causing your leaves to curl.
Smaller plants might get damaged by critters like slugs or snails. You might also deal with common annoyances like root-knot nematodes.
Occasionally the leaves might end up with powdery mildew which looks like white blotches on the leaves.
The kale I grew was mostly being nibbled on by rabbits.
Pest control can be managed pretty easily by covering the crops with some sort of protection like netting, picking pests out by hand, use dish soap mixed with water to kill off aphids, and so on.
Kale is used in a variety of ways. Some like to turn it into soup, many more prefer to throw it into smoothies, my foodie husband is always trying to dice them into frittatas. You can use kale in a wide variety of things.
Baby leaves are nice to add to salads like a regular green. The larger leaves are commonly turned into kale chips. Kale leaves have a tough central stem. You typically want to remove the stem by pulling the leaf part off of the stem part.
Kale is one of my favorite crops to grow and has given me harvests reliably in zone 7 to zone 4. Kale can grow in any climate though the learning curve is figuring out the variety that grows best and the timing aspects of when you want to grow. I hope this helped get you set to grow your own baby kale so you can harvest soon. Spread the love by sharing the article and thank you for stopping by!