By: Mary H. Dyer, Credentialed Garden Writer
Can you grow kale in zone 9? Kale may be one of the healthiest plants you can grow, but it’s definitely a cool weather crop. In fact, a little frost brings out the sweetness, while heat may result in a strong, bitter, unpleasant flavor. What are the best types of kale for zone 9? Is there even such a thing as hot weather kale? Read on for answers to these burning questions.
How to Grow Kale in Zone 9
Nature has created kale to be a cool-weather plant and, so far, botanists haven’t created a truly heat-tolerant variety. This means that growing zone 9 kale plants requires strategy, and perhaps a little trial and error. For starters, plant kale in shade, and be sure to give it plenty of water during warm weather. Here are a few more helpful tips from zone 9 gardeners:
- Plant kale seeds indoors in late winter, then transplant the seedlings into the garden in early spring. Enjoy the harvest until the weather gets too warm, then take a break and resume harvesting your kale when the weather is cooler in autumn.
- Succession plant kale seeds in small crops – maybe a batch every couple of weeks. Harvest the baby kale when the leaves are young, sweet and tender – before they get tough and bitter.
- Plant kale in late summer or early autumn, then harvest the plant when the weather is cool the following spring.
Collards vs. Zone 9 Kale Plants
If you decide that growing hot weather kale is just too challenging, consider collard greens. Collards get a bad rap but, in reality, the two plants are closely related and, genetically, they are nearly identical.
Nutritionally, kale is slightly higher in vitamin A, vitamin C, and iron, but collards have more fiber, protein, and calcium. Both are rich in antioxidants, and both are superstars when it comes to folate, potassium, magnesium, vitamin E, B2, and B6.
The two are usually interchangeable in recipes. In fact, some people prefer the slightly milder flavor of collard greens.
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Read more about Zone 9, 10 & 11
Kale grows best in full sun but will also do well in part-shade. Just be sure it has at least four hours of sun per day. It requires fertile, well-drained soil. It's a good idea to amend your soil with a good amount of compost before planting kale.
You can grow kale in traditional garden beds, raised beds, or containers. If you decide to grow in a container, make sure that the container is at least ten inches deep and that you give the plants plenty of room to grow. You can also add kale to ornamental beds the blue-green leaves of 'Lacinato' or the light magenta stalks and veins of 'Red Russian' add plenty of beauty to a flower bed.
Whether you decide to start these plants indoors or outside, the beauty of growing kale is that it’s simple.
When to Plant Kale
Kale is a cool-season crop, so you can direct sow in the early spring. I prefer to start indoors and set out larger plants when the time comes to transplant. That way, I can harvest sooner once the gardening season begins. Plant indoors 3-5 weeks before last frost date.
When transplanting outside, harden off for 10 days. Transplant when seedlings have 3 leaves and temps reach 50°F.
That said, kale is one of the wonderfully versatile plants that you can transplant or sow nearly anytime during the season. Though it prefers cooler weather, warm summers won’t cause it to bolt or die off. Yet another reason it’s my go-to crop.
If you choose to plant an extremely cold-hardy variety – and there’s no shortage of those in the kale world – for a fall or winter harvest, make sure that the plant has enough time to grow to a large enough size before frost sets in.
You’ll be able to harvest kale all winter long. In particularly cold climates, you might need to protect your kale with a cold frame or heavy mulching, but otherwise, this plant is an excellent source of food in the winter months. In zones 8 through 10, kale can be planted all year round.
Light & Soil Requirements
Kale tolerates partial shade, so if your garden doesn’t get lots of sun, you can still grow this leafy vegetable. Full sun encourages rapid growth, but be sure to mulch around the base to conserve moisture.
Loamy, well-drained soil with a pH between 5.5-6.8 is best, though kale isn’t terribly fussy.
Where to Grow Kale
Kale can be grown anywhere you have space for it. Certain varieties of kale add a decorative element to containers. I often see cities use kale as an ornamental addition to flower plantings. Kale is a good choice for those with limited space (e.g. balcony garden). It does equally well in beds, raised gardens or in-ground.
Kale thrives in zones 7-10.
Kale seeds prefer cooler soil in order to germinate.
Germination time depends on the variety, but generally, kale germinates faster than other plants. You should expect to see sprouts in less than a week.
Spacing depends on the type of kale you’re planting, and I like to experiment a little with spacing. For baby kale greens, I grow four plants per square foot. If I want full sized plants, I plant two per square foot. That’s a minimum of 12-inches between plants.