Raspberry plants can be multiplied easily and affordably using cuttings, a method of vegetative propagation. A cutting is a severed section of a cane that develops its own root system, creating a new, genetically identical clone of the parent plant. This technique ensures desirable traits, such as high yield or disease resistance, are preserved. Propagation uses two primary methods based on the plant’s seasonal growth stage, leading to distinct timing and techniques.
Propagating with Hardwood Cuttings
The best time to take hardwood cuttings is during the dormant season, specifically in late fall after the leaves have dropped or throughout the winter before new growth begins in spring. This timing allows the cutting to focus stored energy on root development rather than supporting foliage. The process involves selecting healthy, mature, one-year-old canes (primocanes) that are firm and woody.
The selected canes should be cut into segments approximately 6 to 8 inches (15 to 20 cm) long, ensuring each piece includes at least two or three dormant buds. Make a straight cut just below a bud at the base and a slanted cut above a bud at the top to easily distinguish the correct planting orientation. This prevents planting the cane upside down, which reduces the chances of successful rooting.
The prepared hardwood segments are inserted two-thirds deep into a sterile, well-draining rooting medium, such as a mix of sand and peat moss. The cuttings require a cool environment, ideally between 35 and 55 degrees Fahrenheit (2 to 13 degrees Celsius), to encourage root formation before shoot growth. They should be stored in a cold frame or a protected, unheated area, kept consistently moist but not waterlogged, until temperatures warm in the spring.
Propagating with Softwood Cuttings
Propagating with softwood cuttings occurs during the active growing season, in late spring or early summer when new growth is tender and flexible. This technique utilizes the plant’s rapid growth phase, but the cuttings are more vulnerable to wilting and desiccation. The ideal material is taken from the tips of non-flowering canes that are still green and pliable, when the new shoots are between 4 and 6 inches (10 to 15 cm) long.
After selecting a healthy tip, all but the top two or three small leaves should be stripped from the bottom of the cutting. This minimizes water loss through transpiration while leaving some foliage for photosynthesis. The freshly cut base is often dipped into a rooting hormone powder or gel, which contains auxins that stimulate root initiation and increase rooting success rates.
The delicate softwood cuttings must be placed immediately into a porous rooting mix, such as perlite or vermiculite, to provide moisture retention and aeration. Creating a high-humidity environment is necessary to prevent the cutting from drying out before roots form. This is achieved by covering the pot with a clear plastic dome or bag, which maintains moisture around the leaves until the new plant can sustain itself.
Care and Establishment of New Plants
Once the cuttings are placed in their rooting medium, the focus shifts to providing stable conditions for root development. The developing plants require consistent soil moisture and excellent drainage to prevent root rot; the soil should never dry out completely. They should be kept in a location that receives bright, indirect light, as direct sunlight can scorch the tender new growth.
After several weeks to a few months, resistance felt from a gentle tug indicates the cuttings have likely formed a delicate root system. Before transplanting outdoors, the young plants must undergo a process called “hardening off.” This gradual acclimation involves progressively exposing the new canes to outdoor elements, such as wind and direct sun, over one to two weeks.
The optimal time for transplanting the newly rooted canes into their final garden location is either the following fall or the subsequent spring. Transplanting during these cooler periods minimizes shock and allows the young plant to establish itself before the stress of summer heat. The new raspberry canes should be planted in well-prepared, well-draining soil, ensuring the root crown is level with the surrounding ground.