Kale is a hardy green vegetable belonging to the Brassica oleracea species, which also includes cabbage and broccoli. This nutritious crop is valued for its ability to withstand colder temperatures, making it a staple in many growing seasons. Propagation is the process of creating new plants from an existing source, allowing gardeners to multiply their stock or preserve favorite varieties. Understanding methods like sexual propagation through seeds and vegetative propagation via cuttings helps maintain a continuous supply of this leafy green.
Starting Kale Plants from Seed
The most common method for starting kale involves planting seeds indoors or directly in the garden. Starting seeds indoors about six weeks before the last expected frost date gives plants a head start in cooler spring weather. Sow the seeds one-quarter to one-half inch deep in a sterile seed-starting mix, ensuring the medium remains consistently moist.
Kale seeds generally germinate quickly, often sprouting within five to twelve days. Once seedlings develop their first set of true leaves, thin them to allow the strongest plant to grow. Before transplanting, young plants must undergo a hardening-off period, which gradually acclimates them to outdoor conditions like wind and direct sun.
For direct sowing, wait until the soil temperature reliably reaches at least 45°F, planting seeds a quarter-inch deep and spacing them three inches apart initially. The soil should be well-draining and enriched with organic matter, as kale benefits significantly from high nitrogen content for robust leaf growth. Seedlings must be thinned to a final spacing of 18 to 24 inches apart to ensure good air circulation and adequate nutrient access.
Propagating Kale Using Stem Cuttings
Propagating kale through stem cuttings is a vegetative reproduction method useful for cloning a desirable plant or extending the life of a perennial variety. Select a healthy, non-flowering side shoot or secondary stem, avoiding the central growing point of the plant. The cutting should include several leaf nodes, which are the points where roots will emerge.
Prepare the cutting by removing the lower leaves to prevent them from rotting and make a clean cut just below a node. Dipping the cut end into a rooting hormone can accelerate root development, though many kale varieties will root successfully without it. Place the cutting into a container filled with a moist, soilless potting mix or well-drained compost, ensuring at least one node is buried below the soil line.
Roots typically begin to form within a few weeks, especially if the rooting medium is kept consistently damp and the cutting is protected from harsh sun. This method bypasses the seed-starting stage, allowing for the rapid establishment of new plants that are genetically identical to the parent. Cuttings can be taken from established plants and transplanted into the garden once a sturdy root system has developed.
Collecting and Storing Kale Seeds
Collecting kale seeds requires patience because kale is a biennial plant. This means the plant needs two full growing seasons, including a period of cold weather, to complete its life cycle and produce seed. Plants must be allowed to overwinter and then bolt, or send up a flowering stalk, in their second year.
Kale flowers will eventually develop into long, thin seed pods called siliques. These pods start green and must be left on the plant until they turn brown, become dry, and feel brittle to the touch. Once the pods are thoroughly dried, the entire stalk can be cut and inverted into a large paper bag to capture any seeds that drop.
Threshing involves shaking or gently rubbing the dried pods to release the small, dark seeds. The seeds must then be cleaned of the remaining plant material, known as chaff, through winnowing. Store the clean seeds in a cool, dark, and dry location, such as a sealed glass jar in the refrigerator, where stable temperatures around 50°F and low humidity help maintain viability.