Greetings from the botanical world. We, the Grevillea family, are a diverse and sun-worshipping group, originally hailing from the sun-drenched landscapes of Australia. While some of our kin are adaptable to indoor life, our fundamental need for abundant light remains unchanged. To truly thrive inside your home, understanding our specific sunlight requirements is paramount.
At our core, we are heliotropic plants, meaning we grow towards and flourish under direct sunlight. In our native habitats, we bask in full sun for the majority of the day. This intense light fuels the photosynthetic processes that create our energy, supports the development of our strong, woody stems, and is the single most critical factor in triggering our magnificent and intricate blooms. For us, sunlight is not a luxury; it is sustenance. Without several hours of direct sun daily, we will become leggy, with weak, elongated stems straining for any available light. Our foliage may fade from a healthy green to a pale, yellowish hue, and we will almost certainly refuse to flower, losing a key part of our identity.
To best replicate our natural preferences indoors, placement is everything. The optimal location for us is directly in front of a south-facing window (if you are in the Northern Hemisphere). This exposure provides the most consistent and intense direct sunlight throughout the day, which is precisely what we crave. An unobstructed west-facing window can also be suitable, as it provides strong afternoon sun, though the intensity and duration may be slightly less than a southern exposure. East-facing windows offer only gentle morning sun, which, while beneficial, is often insufficient as our sole light source. A north-facing window is, unfortunately, a recipe for decline, as it provides barely any direct light and will leave us languishing.
It is not enough to simply be near a bright window; we require prolonged exposure. Our photosynthetic machinery operates most efficiently with a minimum of six hours of direct sunlight each day. More is always better, aiming for eight or more hours if possible. The intensity of this light is also vital. The unfiltered rays of the sun through a clean window provide the spectral quality we need for robust growth. While we can tolerate some very light shading, any significant obstruction like trees, buildings, or window screens will drastically reduce the light's intensity and compromise our health. Rotating our pot a quarter turn every week is also appreciated, as it ensures all sides of our structure receive equal light and prevents us from becoming lopsided.
We understand that not every human dwelling has the perfect sunny window. In such cases, you can supplement our light diet with artificial grow lights. These are not ordinary household lamps but full-spectrum lights designed to mimic the sun's rays. To be effective, the light source should be placed quite close to us—approximately 6 to 12 inches above our foliage—and kept on for 12 to 16 hours a day to compensate for its lower intensity compared to the actual sun. This artificial day extension can successfully prevent etiolation (weak, stretched growth) and may even encourage budding.
