From my perspective as a Grevillea, the timing of your cut is crucial for my successful propagation. My cells divide most actively when I am in a period of vigorous growth, typically from late spring through early autumn. This is when my vascular system is pumping with energy, and the hormones that trigger root formation are at their peak. The ideal moment is after a flush of growth has begun to harden slightly but is not yet fully mature and woody. This semi-hardwood state offers the perfect balance of youthful cellular plasticity and enough structural integrity to resist rotting. Taking cuttings in the intense heat of midsummer can place undue stress on both me and the cutting, so slightly cooler periods within the growing season are best.
When you choose a stem from which to take a cutting, you are selecting a potential new individual. Please look for a healthy, disease-free branch from my current season's growth, about 4 to 6 inches long. The cut you make must be clean and sharp, using sterilized pruners just below a leaf node. This node is a hub of cellular activity; it is where my latent root cells, called meristematic tissue, reside. Immediately after severing me from the parent plant, I begin to panic, losing moisture rapidly. To mitigate this shock, you should gently remove the leaves from the lower half of my stem. This reduces transpiration and prevents decayed foliage from contaminating the rooting medium.
While I possess the innate ability to produce roots, the application of a rooting hormone powder significantly boosts my chances. This powder contains synthetic auxins, which are plant hormones that stimulate root initiation. For my semi-hardwood stems, a formulation with a moderate hormone concentration (0.3% IBA) is ideal. Before you dip my basal end into the powder, ensure the stem is slightly moist to help the powder adhere. A gentle tap removes any excess. This simple step acts as a powerful signal to my cells, redirecting their energy from maintaining foliage to the urgent task of building a new root system.
I cannot be placed in standard potting soil at this fragile stage. It is too dense, retains too much moisture, and likely contains pathogens that would cause my tender stem to rot. My first home must be sterile, well-draining, and porous to allow for oxygen exchange around my developing root sites. A mix of equal parts perlite and coarse horticultural sand or a peat-perlite blend provides the perfect physical support and moisture balance. Pre-moisten this medium before you place me inside it. Make a hole with a pencil first to avoid wiping off the precious rooting hormone, then firm the medium gently around my stem.
My most critical need now is consistent humidity. Without roots, I cannot replace the water I lose through my remaining leaves. You must create a miniature greenhouse for me. Covering my pot with a clear plastic bag or placing me under a humidity dome maintains a saturated atmosphere around my foliage, drastically reducing water loss. However, this environment must be bright yet out of direct, scorching sunlight, which would cook me. Gentle bottom heat, around 70-75°F (21-24°C), provided by a propagation mat, will further encourage my roots to develop faster than my shoots. Check my medium periodically; it needs to be consistently damp but never waterlogged.
