Kale is commonly treated as an annual vegetable, yet it is botanically a biennial plant that can live for two years. Propagating kale from cuttings is a method of vegetative reproduction, allowing a gardener to create an exact genetic copy of the parent plant without using seeds. This technique is useful for maintaining a favored variety’s specific traits or for extending the harvest of a mature plant into a new growing season.
Selecting and Preparing the Cutting
Selecting a healthy stem is crucial for successful propagation. Choose a non-flowering side shoot or “sucker” emerging from the main stalk, ideally measuring four to six inches in length. Select the cutting from the lower or middle section of the parent plant, avoiding the central growing point.
Use a clean, sharp knife or shears to make a precise cut just below a leaf node. The node is the slightly swollen point where a leaf attaches and holds dormant cells that develop into new roots. After harvesting, gently strip away all leaves from the lower two-thirds of the stem.
Removing the lower leaves prevents them from rotting when submerged in water or buried in soil. The bare nodes along the lower stem must be exposed, as this is where the new root system will emerge. The remaining leaves at the top will sustain the cutting through photosynthesis while roots develop.
Rooting the Kale Cuttings
Kale cuttings can be rooted using two primary methods. The water method involves placing the prepared stem into a clear container filled with clean water, ensuring at least one node is submerged. Change the water every few days to maintain oxygen levels and prevent bacterial growth.
Although the water method allows for easy monitoring, rooting in a growing medium often leads to a more robust plant better suited for transplanting. For this approach, use a sterile, well-draining mix, such as perlite and peat moss. Insert the cutting deeply so that several nodes are buried, then gently firm the mix around the stem.
Maintaining high humidity is important for cuttings rooted in a potting mix, as it reduces moisture loss from the leaves until the roots can form. This can be achieved by placing a clear plastic dome or bag loosely over the pot to create a mini-greenhouse effect. Keep the container in a warm location with bright, indirect light, and roots should begin to form within three to four weeks.
Transitioning Rooted Cuttings to the Garden
Once new roots are visibly established and measure at least two to four inches long, the young kale plant is ready for a gradual transition outdoors. This process, known as “hardening off,” acclimates the cutting to direct sun, wind, and fluctuating temperatures. Begin by placing the rooted cutting outdoors in a shaded, protected area for a few hours each day.
Over a period of about seven to ten days, progressively increase the amount of time the plant spends outside and the intensity of the light it receives. This slow exposure helps the plant develop stronger cell walls, reducing the risk of transplant shock. Skipping this step can lead to scorched leaves and stunted growth when the plant is moved permanently.
When planting into the garden, dig a hole deep enough to bury the main stem slightly deeper than it was in the pot. This placement encourages additional root growth along the buried stem, resulting in a more secure and stable plant. Water the newly planted kale thoroughly and maintain consistent moisture for the first few weeks to support the developing root system.