Kale is a popular, nutrient-dense leafy green that thrives in cooler temperatures, making it a garden favorite for both spring and fall harvests. Achieving a successful harvest begins with precise planting techniques, which directly influence the plant’s initial establishment and long-term productivity. This guide offers specific, actionable instructions for planting both kale seeds and transplants to ensure vigorous growth from the start.
Preparing the Planting Site
Kale performs best in full sun but tolerates partial shade, especially where temperatures frequently rise above 75°F. It is a cool-weather crop, growing most vigorously when temperatures are between 55°F and 75°F. Planting should be timed for early spring or late summer to allow the plants to mature before the peak heat or winter freeze.
The foundation for healthy kale is fertile, well-drained soil that is rich in organic matter. Prior to planting, amend the area with a layer of compost to provide a consistent source of nitrogen, which supports lush leaf production. Kale prefers a soil pH range of 6.0 to 7.5, and a soil test can help determine if amendments are needed. Consistent moisture is necessary for the highest-quality leaves, so choosing a site that drains well is important.
Specific Depth and Spacing Instructions
The depth at which kale is planted is determined by whether you are sowing seeds or setting out established transplants. When direct sowing kale seeds, the correct depth is shallow, typically between 1/4 and 1/2 inch deep. Covering small seeds with too much soil can prevent the emerging cotyledons from reaching the surface. Gently firm the soil over the seeds to ensure good seed-to-soil contact, which is necessary for proper germination.
For direct seeding, sow the seeds about one to three inches apart initially. You will thin them later to ensure adequate room for mature growth. Mature plants require generous spacing to allow for a large leaf canopy and to promote good air circulation, which helps prevent disease. Individual plants should be spaced 18 to 24 inches apart in the row, with rows separated by 18 to 36 inches.
When planting kale transplants, the depth is determined by the size of the root ball in its original container. Dig a hole only as deep as the container and place the root ball so the top of the soil is level with the garden bed soil. If the seedling is “leggy,” meaning it has a long, pale stem, you may set it slightly deeper, but avoid burying the terminal bud or the first set of true leaves. Handle the root ball gently to minimize transplant shock.
Establishing Young Kale Plants
Immediately after planting either seeds or transplants, a deep and thorough initial watering is necessary to settle the soil around the roots or seeds and eliminate air pockets. Consistent moisture is particularly important for germinating seeds, which require the top layer of soil to remain damp until the seedlings emerge. This initial watering also helps transplants begin to establish their root systems in the new environment.
If kale was direct-sown, the seedlings will need to be thinned once they develop three to four true leaves. Thinning involves removing the weaker seedlings to achieve the final recommended spacing. This practice reduces competition for water and nutrients and allows the foliage to dry more quickly, reducing the risk of fungal issues.
Protecting the young plants from early pests and unpredictable weather is important. Floating row covers, lightweight fabric draped over hoops, can be applied immediately after planting to exclude common pests like cabbage worms and flea beetles. These covers also offer a few degrees of frost protection, which is beneficial if planting in the early spring before the last expected frost date.