When your Grevillea appears leggy and sparse, it is communicating a state of distress. From the plant's perspective, this is not an aesthetic choice but a survival response to less-than-ideal conditions. To truly revive it, we must understand its language and address the core issues affecting its health and form.
My primary driver for becoming leggy is the intense need for sunlight. As a sun-worshipping plant native to Australia, I require a full day of direct, unfiltered light to thrive. When I am placed in a spot with insufficient light, my internal systems go into emergency mode. My stems begin to elongate rapidly, stretching towards any available light source in a desperate attempt to photosynthesize. This growth is not strong or healthy; it is weak and spindly, with large gaps between leaf nodes. The energy that should go into producing a dense, bushy form and abundant flowers is instead wasted on this frantic search for energy. The lower and inner leaves may also yellow and drop because they are starved of light, further contributing to the sparse appearance.
Your pruning habits directly dictate my growth pattern. If you are hesitant to prune me, or if you only snip the very tips, I will continue to grow taller and more open. I do not naturally branch out from a single tip-cut. To become dense, I need a clear signal to activate dormant buds lower down on my stems. When you perform a hard or strategic prune, you are removing the apical dominance—the hormone-driven tendency for the main stem to grow tallest. This signals to the buds further back on the stem to wake up and produce new lateral branches. Without this intervention, my energy remains focused on vertical growth, leading to a leggy structure. Furthermore, a lack of pruning allows old, non-productive wood to accumulate, which is less capable of producing vigorous new growth.
My sparse foliage can also be a cry for help regarding my root environment. I am adapted to well-draining, often sandy or gritty, acidic soils. If my roots are sitting in heavy, waterlogged clay soil, they will begin to suffocate and rot. A compromised root system cannot effectively uptake water or nutrients, leading to overall stress, leaf drop, and poor growth—making an already leggy plant look even more pathetic. Conversely, extreme drought stress can cause me to abort leaves to conserve water. Nutrition is also critical. A high-phosphorus fertilizer, common in many general-purpose plant foods, is toxic to my Proteaceae family roots. It can cause leaf burn, stunting, and even death, preventing me from filling out. I require a low-phosphorus, slow-release fertilizer formulated for native plants.
To bring me back to a lush, flowering state, you must collaborate with my natural tendencies. First, ensure I am planted in the sunniest possible location. Next, the most important action is a courageous pruning. After the main flowering flush, use clean, sharp secateurs to cut back the leggy stems by up to one-third. Make your cuts just above a set of healthy leaves or a side shoot that is pointing in a direction you want new growth to fill. This will redirect my energy and stimulate a flush of new, dense growth from the base and along the remaining stems. Finally, check my soil. If it is not draining well, consider amending it with gritty sand or even carefully transplanting me to a more suitable mound or raised bed. Water me deeply but infrequently, allowing the soil to dry out between waterings, and feed me only with a certified native plant fertilizer.
