With any kind of vegetable, it’s difficult to find out when is the optimal time to start planting. Kale is quickly becoming my favorite leafy salad green, and what I’ve found is that unlike lettuce and spinach, kale can be grown in any time of the year without turning bitter.
When Should I Plant Kale?
Kale can be planted any time from 8 weeks before your average first frost date to late summer (or about 80 days before your last frost date), and can be direct sown outdoors or indoors. If sown indoors, plant out the transplants when they have a few healthy leaves and are a couple inches tall. Kale is frost hardy down to 10°F (-12°C), and if you have a greenhouse or very mild winters, you can grow kale all year round, but kale will grow more slowly in the winter months.
Best Time to Plant Kale
Since kale can grow any season without consistent frost, you can plant anytime from 8 weeks before your average last frost date up to well into the fall. Transplant after your kale is a few inches tall and has a few sets of healthy leaves.
You can even direct sow outside before your last frost, as long as the soil is workable, but covering the ground with some plastic will speed up germination.
I like to start most of my kale indoors around 6 weeks before my last frost. If I want more kale plants later on and have the space for it, I will sow more seeds up to August so my kale seedlings have enough time to grow quickly in the warm weather before colder temperatures slow down growth.
If you have a greenhouse or plastic row covers to extend your season, you can plant even sooner. Some warm climates even allow year-round kale sowing and growing.
Kale’s Growing Season
Kale is unlike a lot of leafy green vegetables in that it can grow all year long. Lettuce, spinach, and arugula, for example, will all bolt (produce a flower stalk) when the weather gets too hot. Bolting generally means the leaves will become smaller and much more bitter.
Kale is a biennial, so it normally won’t produce flowers and seeds until the following year. Even when it does bolt, the taste of kale doesn’t change much, and the buds can be harvested and eaten like little broccoli florets.
Kale can also survive winter temperatures down to 10°F (-12°C). If you have mild winters or you grow your kale under plastic row covers or in a greenhouse, you can even grow kale and get harvests through the winter as well. Just keep in mind that kale will grow much more slowly as you get closer to freezing temperatures.
How Long Does It Take to Grow Kale?
Depending on the variety, you can harvest your first medium to to large kale leaves around 50 to 60 days from transplanting or 70 to 80 days from seed. Of course, if you want baby kale, you can often get your first harvest in anywhere from 10 to 20 days sooner.
When harvesting kale, most gardeners (including myself) recommend using the cut-and-come-again method of harvesting, which involves removing the lower leaves while keeping the top few leaves to give your kale plants energy to keep growing.
Combining the fact that kale can be successfully grown any time there isn’t persistent frost with cut-and-come-again harvesting means you can keep getting consistent harvests every 1 to 3 weeks (less often in the colder months) from each kale plant until the frost pauses growth completely.
Does Kale Grow in Hot Weather?
Kale, unlike many other leafy greens, does grow in hot weather. While kale tastes sweeter in cool weather, it grows faster in warm weather.
Kale is very unlikely to bolt in the first year unless under extreme heat or drought stress, or if it goes through an unusually cold period followed by another warm period.