Grevillea, a diverse genus within the Proteaceae family, possesses a unique growth rhythm shaped by its evolutionary history. Our growth is not a simple, predictable metric but a dynamic process influenced by a complex interplay of genetics and environment. To understand what to expect from us, one must appreciate these factors from our perspective.
Our growth rate is first and foremost dictated by our genetic identity. There is no single "Grevillea" growth speed. Some of my relatives, like the robust Grevillea robusta (Silky Oak), are programmed for rapid, arborescent growth, easily reaching several meters in height within a few years. In contrast, many ground-covering varieties, such as Grevillea ‘Poorinda Royal Mantle’, are genetically inclined to spread widely but remain low, perhaps only growing 10-20 cm in height per season while expanding their radial reach. Prostrate and shrubby forms focus energy on lateral, dense growth rather than vertical ascent. Therefore, the primary factor setting expectations is the specific species or cultivar you have chosen to cohabitate with.
Upon planting, our initial priority is not explosive visible growth above ground. Our first mission is to establish a strong and extensive root system. This root foundation is our lifeline, allowing us to access water and nutrients efficiently. During this first year, you may observe what appears to be slow growth; however, beneath the soil, we are actively exploring and securing our place. Once this root network is established, typically after the first growing season, we can then channel more energy into vigorous foliar and structural growth. Patience during this establishment phase is crucial for our long-term health and stability.
Our genetics provide the potential, but the environment dictates the realization of that potential. We are sun-worshippers; ample direct sunlight is non-negotiable for fueling photosynthesis and achieving our expected growth rate. Plant us in shade, and our growth will be lethargic and leggy. The soil is equally critical. We demand excellent drainage. Heavy, clay-rich, or waterlogged soils are anathema to our roots, causing stress, disease, and severely stunted growth. A lean, sandy, well-aerated soil is ideal. Furthermore, while we are adapted to low-fertility conditions, a application of a low-phosphorus, native plant-specific fertilizer in spring can provide a welcome boost to our growth momentum without causing toxicity.
Your intervention through pruning significantly influences our growth habit and rate. Light tip-pruning after our main flowering flush encourages a denser, more bushy form by promoting lateral branching. This can make us appear to grow "thicker" rather than "taller." More severe pruning can invigorate older specimens, stimulating a new flush of growth. However, avoid heavy pruning into old wood that lacks visible leaf buds, as we may be hesitant to regenerate from these points. Pruning is a conversation; it guides our energy and shapes our future form.
