What Month Should You Sow Kale?

If you’re deciding when to sow kale, there are a number of factors to consider. These include the time of year, your growing zone, your desired harvest date, and the available growing conditions.

A close up of freshly harvested curly kale leaves, their dark green color contrasting with the lighter veins. In the center and at the bottom of the frame is green and white text across the image.

One of the best things about this hardy green is that it is fairly flexible in terms of when you may start growing it, and a few weeks’ difference won’t set your plants back too much.

Here’s what’s to come in this article:

When to Sow Based on Hardiness Zone

Your USDA Plant Hardiness Zone is an important factor to consider when you are deciding what month to sow kale. You can read more about these hardiness zones here.

Close up of a seed tray containing lots of kale seedlings, the green of the leaves contrasts with the dark potting mix they are planted in.

Those who live in a hardiness zone with a high number can start growing earlier in the spring and later in the fall than those who live in a hardiness zone with a low number. As the hardiness zone number increases, the growing season gets longer.

Other useful information for determining the planting date is your predicted last frost date in the spring, and first frost date in the fall.

When to Sow in the Spring and Fall

Kale is a cool weather crop, so it grows best in the spring and fall.

In the spring, you can plant seeds outside immediately after the last frost. At this point, the soil will have warmed enough for germination to occur. You can continue to sow seeds until the end of May.

A hand on the left side of the frame holding tiny seeds of Brassica oleracea ready for planting. In the background is a seed starter tray with potting mix in each section.
Photo by Briana Yablonski

If you are starting seedlings indoors, sow four to six weeks before the predicted last frost date.

For example, where I live in Zone 7a, the predicted last frost date is April 18. Therefore, I start seeds indoors in trays the first week of March. I love watching this new life grow when it is still cold and gray outside.

In the fall, you should start seeds early enough that plants have time to mature before the days draw in, and become too short.

The latest you should try to grow plants from seed depends on what organic gardening writer Eliot Coleman refers to as the Persephone Period, referenced in his book The Winter Harvest Handbook, which is available on Amazon. This is the time when days are less than ten hours long.

The Winter Harvest Handbook: Year Round Vegetable Production Using Deep-Organic Techniques and Unheated Greenhouses

For baby leaves, the latest you should plant is six weeks before this period. If you’re aiming for full-sized leaves, sow no later than 13 weeks before this period.

Depending on your region, this means you should plant seeds directly in the garden from mid-July to mid-September. You can start trays for transplants in June, July, or August, and plant these out into your garden in late July to late September.

How to Time Succession Plantings

If you’re growing baby kale, planting seeds once and then again a few weeks later will allow for a continuous supply. This tactic of sowing multiple plantings is known as succession planting. You can read more about succession planting here.

A close up of Brassica oleracea seedlings, still in their seed tray, ready for transplanting into the garden. The green of the leaves contrasts with the dark earth in the background.

Aim to plant seeds directly in your garden every two to three weeks.

When there is less daylight, plants will grow more slowly, so successive plantings should be sown closer together, over shorter periods of time. In March and November, space successions two weeks apart. In May, June, September, and October, space them three weeks apart.

Sow Some Kale Seeds

Now that you know when to plant, you can start planning how it will feature in your garden. Whether you’re planting in the spring or fall, this tasty, nutritious green makes a great addition.

A close up of little green kale seedlings, with beads of water on some of the leaves, the background is more of these seedlings, and the dark earth underneath them in soft focus.

If you have questions about when to plant seeds in your specific area, feel free to ask in the comments.

To read more about growing this versatile, nutritious leafy green, check out these articles:

Photo by Briana Yablonski © Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Book cover image via Chelsea Green Publishing. Uncredited photos: Shutterstock.

About Briana Yablonski

Briana Yablonski grew up in Eastern Pennsylvania and currently resides in Knoxville, Tennessee. She holds a Bachelor of Science degree in plant sciences and has worked on farms in Minnesota, Pennsylvania, Virginia, and Tennessee. Now, she spends many hours planting seeds and moving compost at her market garden. When she’s not immersed in the world of gardening, Briana enjoys walking dogs at the local shelter and riding her bike. She believes that gardening fosters curiosity, continuous learning, and wonder.

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