Evergreen propagation is the process of creating new plants from a parent tree or shrub, allowing gardeners to multiply their favorite varieties. This reproduction ensures the continuation of desirable traits or the expansion of a species population. Evergreens are generally propagated using two primary methods: stem cuttings or seeds. The method chosen depends largely on the specific plant species and the grower’s goal.
Choosing the Best Propagation Method and Timing
The selection between using a cutting or a seed is determined by the required genetic outcome. Cuttings produce clones, which is the preferred method for maintaining the unique characteristics of a named cultivar or hybrid. Conversely, seeds introduce genetic variation, making this method more suitable for propagating true species where slight differences are acceptable or desired.
Timing for cuttings is divided into two periods to utilize the plant’s growth cycle. Semi-hardwood cuttings, taken in late summer or early fall, use wood that is partially matured but still flexible. Hardwood cuttings are taken in winter, utilizing fully mature, dormant stems after the leaves have dropped or the growth has hardened. For seed propagation, collection usually occurs in the fall when the cones or fruits ripen, allowing the seeds to be prepared for spring sowing.
Step-by-Step Guide to Stem Cuttings
Successful propagation begins with selecting material from a healthy parent plant. Cuttings should be taken from non-flowering shoots, often from the lower, shaded branches, as this wood roots more readily. Many evergreens respond well to a “heel” cutting, where the lateral shoot is gently pulled away from the main stem, retaining a small strip of the older bark.
The cutting should be approximately 4 to 6 inches long. Remove the needles or leaves from the bottom third to two-thirds of the stem to expose the nodes, which are the sites where new roots will form. This prevents the foliage from rotting when buried in the medium, which could introduce disease.
After preparation, the base of the cutting is dipped into a rooting hormone, typically a powder containing auxins, to stimulate root development. The hormone powder should cover the exposed tissue, including the heel if one was taken.
A well-draining rooting medium is then prepared, often a sterile mix of peat moss and perlite or coarse sand. This combination retains some moisture while ensuring excellent aeration, which is important for root formation. The prepared cutting is inserted into the medium, ensuring the exposed nodes are buried and the cutting stands upright.
Environmental control is important for evergreen cuttings, which benefit from high humidity to prevent desiccation before roots form. Placing the planted cuttings under a plastic dome or inside a plastic bag creates a miniature greenhouse effect. Maintaining a consistent, warm temperature, ideally around 65 to 75 degrees Fahrenheit, and providing bright, indirect light encourages rooting.
Growing Evergreens from Seed
Propagating evergreens from seed requires overcoming dormancy. Most evergreen seeds require a period of cold, moist exposure called stratification to break this dormancy. This process is necessary because chemical inhibitors within the seed must be broken down before germination can begin.
To stratify seeds artificially, they are often mixed with a moist substrate like peat moss, vermiculite, or sand. This mixture is sealed in a plastic bag or container and stored in a refrigerator at temperatures between 33 and 41 degrees Fahrenheit. The duration of this cold, moist treatment ranges from one to four months, depending on the species, simulating the required winter period.
Once the stratification period is complete, the seeds are ready for sowing. They are planted in a finely textured seed-starting mix, then lightly covered with the medium. Sowing the seeds in spring allows them to germinate as temperatures naturally rise, providing the seedlings with a full growing season to establish themselves. Keeping the seedbed consistently moist and protected from direct sun is important during this initial growth phase.
Rooting and Transplanting Success
After several weeks or months, depending on the species and method, the propagated material will develop roots. To check for root formation on a cutting, gently tug on the stem; resistance indicates that roots have begun to anchor the plant. Seedlings are confirmed to be established once they have produced their first set of true leaves and show robust, steady growth.
Before moving the newly rooted plants to a permanent location, they must undergo a process called “hardening off.” This gradual acclimation toughens the plant tissue and prepares the evergreen for the less controlled environment outdoors. Hardening off involves slowly introducing the plants to increased sunlight, wind, and fluctuating temperatures over a period of seven to fourteen days.
The process begins by placing the plants outdoors in a shaded, sheltered spot for just a few hours each day, bringing them back inside at night. Over the next week, the duration of outdoor exposure is increased daily, and the plants are gradually moved into areas with more direct sunlight and wind exposure. Once the young plants are fully acclimated, they can be safely transplanted into a larger pot or directly into the garden, ensuring the root ball is not damaged during the transition.