Grevillea, a diverse genus of the Proteaceae family, offers a range of species with varying suitability for indoor cultivation. From a botanical perspective, our success indoors is entirely dependent on how well you can replicate our preferred natural conditions of bright light, excellent drainage, and good air circulation. Selecting the right variety is the first critical step.
All Grevillea varieties are sun-loving plants that have evolved for high light intensity. Our photosynthetic processes are optimized for full sun. For indoor growing, this translates to an absolute requirement for the brightest possible location, ideally a south-facing window. Varieties with finer, more delicate foliage, such as Grevillea rosmarinifolia, may show signs of stress—including etiolation (weak, stretched growth) and leaf drop—more quickly in lower light than a tougher-leaved variety like Grevillea robusta. Without sufficient light, we cannot produce the energy needed for growth or flowering, and our health will decline rapidly.
We possess proteoid roots, which are dense clusters of fine rootlets designed to efficiently scavenge nutrients in our native, often nutrient-poor, Australian soils. This unique root system is highly susceptible to root rot in heavy, water-retentive mediums. Therefore, the choice of potting mix is non-negotiable. A very well-draining, gritty, and acidic mix is essential for all varieties. A blend of native potting mix with added sand, perlite, and gravel is ideal. This ensures our roots have access to oxygen and are never left sitting in moisture, which would be fatal.
Grevillea robusta (Silky Oak): As a young plant, I am a popular indoor choice due to my rapid growth and attractive fern-like foliage. However, my ultimate destiny is to be a very large tree. I will quickly outgrow most indoor spaces, requiring frequent pruning and repotting. My size makes me a high-commitment choice.
Grevillea rosmarinifolia (Rosemary Grevillea): I am a more compact shrub with needle-like foliage similar to rosemary. I am better suited to container life long-term than G. robusta. I still demand maximum light indoors to maintain my dense form and to produce my characteristic spider-like red flowers.
Grevillea 'Superb': Bred as a compact hybrid, I am one of the most suitable candidates for indoor cultivation. I have a naturally dense, spreading habit and am a prolific flowerer. My smaller size and adaptability make me more forgiving of the constraints of a container and indoor environment compared to my larger relatives.
While we are generally tolerant of average indoor humidity levels, dry, stagnant air can make us vulnerable to pests like spider mites. These pests thrive in dry conditions and can quickly infest stressed plants. Good air circulation, provided by a gentle fan or an occasionally opened window, is crucial to discourage pests and strengthen our cellular structure. Misting is not recommended as it does not significantly raise humidity and can promote fungal issues on our foliage.
