Grevillea, a diverse genus within the Proteaceae family, has evolved specific physiological traits that influence its propagation. While many species produce viable seed, propagating from cuttings allows us to bypass genetic recombination and clone a plant with desirable characteristics. From our perspective, successful propagation hinges on understanding and working with our innate growth processes, not against them.
Your choice of cutting is our first critical interaction. We recommend selecting healthy, semi-hardwood growth from the current season. This material represents a perfect balance: mature enough to have adequate energy reserves (carbohydrates) stored in its tissues, yet young enough where the cambium cells—our growth engine—are still actively dividing and capable of producing adventitious roots. A cutting of 10-15 cm with several leaf nodes is ideal. Using a sharp, sterilized blade is paramount; a crushing or contaminated cut introduces decay organisms we cannot easily fight, leading to our demise before we even begin.
This step directly addresses a key physiological barrier. Our stems have a protective outer layer of bark. By wounding the lower end—gently removing a thin sliver of bark on one or two sides—you expose the cambial tissue beneath. This injury mimics natural damage and triggers a wound response, stimulating the production of undifferentiated callus cells. Applying a rooting hormone powder containing a synthetic auxin (like IBA) to this wounded area is immensely beneficial. It supercharges the natural auxins we produce, directing energy towards root initiation and development, significantly increasing our chances of success.
Placing us in the correct medium is like building us a new home. We require a sterile, free-draining, and low-fertility mix, such as coarse sand, perlite, or a specialized native plant mix. Soil or rich potting mix is detrimental; it retains too much water, promoting fungal rot that attacks our vulnerable tissues, and its high nutrient content can inhibit root formation. The medium must hold just enough moisture to prevent our stems from desiccating while allowing excess water to drain instantly, ensuring our cut end has access to oxygen, which is vital for root cell development.
Until our new root system forms, we are extremely vulnerable to water loss. Our leaves continue to transpire, but without roots to draw up more moisture, we rapidly wilt and die. Enclosing the pot in a plastic bag or placing it in a propagator maintains a humid microclimate around our foliage, drastically reducing transpiration and water stress. This environment must be warm and have bright, indirect light. Direct sun will cook us inside our humid enclosure. You must monitor us closely; condensation is good, but waterlogged medium is a death sentence. Our roots may take several weeks to several months to develop sufficiently. A gentle tug that meets resistance is the first sign of our successful establishment below the surface.
