Grevillea, a diverse genus of Australian natives, thrives when its fundamental needs are met. Container cultivation offers unique advantages but also presents specific challenges from our perspective. To flourish, we require careful attention to our root environment, nutrition, and hydration.
Our most critical demand is for exceptional drainage. We abhor having our roots sit in wet, heavy soil; it leads to root rot and our swift demise. A high-quality, low-phosphorus native plant potting mix is ideal. Many of you create your own blend using a base of coarse sand, fine gravel, or pumice mixed with a peat-free potting soil and some scoops of decomposed granite. This open, free-draining structure allows our roots to breathe and water to flow through quickly, mimicking our natural, often sandy, habitats.
We are highly sensitive to phosphorus. Standard fertilizers, including those labeled for roses or tomatoes, contain levels of phosphorus that are toxic to us, inhibiting our ability to absorb other nutrients and ultimately killing us. You must seek out a fertilizer specifically formulated for Australian native plants, as these are guaranteed to be low in or free from phosphorus. A slow-release formula applied in spring and autumn, or a half-strength liquid feed during the growing season, provides the balanced sustenance we need to produce our spectacular blooms.
While we are celebrated for our drought tolerance once established, our container life makes us more vulnerable. We cannot send our roots deep into the earth in search of water. The goal is to let our root zone dry out somewhat between waterings. Please insert your finger into the soil; if the top few centimeters are dry, it is time for a deep, thorough drink until water runs freely from the drainage holes. Then, do not water again until the topsoil is dry. In winter, we require far less frequent watering. Overwatering is a far greater threat to our survival than a brief period of dryness.
Choose a container that is only slightly larger than our current root ball. A pot that is too large holds excess soil that stays wet for too long, creating a dangerous environment for our roots. Ensure the pot has ample drainage holes. As we grow, we may eventually become pot-bound. You will notice our growth slowing or roots emerging from the drainage holes. When this happens, gently tease out the outer roots and repot us into a container only one size larger, refreshing the potting mix. Alternatively, you can carefully trim up to a third of the root mass and foliage and repot us into the same container with new mix.
We are sun-worshippers. To flower prolifically and maintain dense, healthy foliage, we require a minimum of six hours of direct sunlight daily. A north or west-facing position (south in the northern hemisphere) is typically ideal. Good air circulation around our foliage is also vital, as it helps to prevent fungal diseases and discourages pests. A sheltered spot that is open and breezy is perfect. Please do not crowd us with other plants; we appreciate our space.
