Grevillea houseplants, with their intricate, spider-like blooms and fine, needle-like foliage, are not just visually striking but also wonderfully communicative. Understanding their watering needs requires listening to the plant itself and its environment, rather than adhering to a rigid calendar schedule. From our perspective, our needs are dictated by a delicate balance between thirst and a profound aversion to suffocation.
Our root systems are adapted for well-draining, often sandy or gritty, native Australian soils. We despise having our roots sit in consistently wet, heavy, or waterlogged potting mix. This environment invites root rot fungi, which will quickly attack and decay our roots, cutting off our water and nutrient supply, leading to a rapid and often fatal decline. Therefore, the golden rule is to water deeply but infrequently, allowing the potting medium to dry out significantly between drinks.
We provide clear signals about our hydration status. The most reliable method is the touch test. Insert your finger into the top 2-3 inches (5-7.5 cm) of the soil. If it feels completely dry to the touch, it is time for a thorough watering. If it still feels cool or slightly damp, please wait. You can also lift the pot; a pot that feels very light for its size indicates the soil is dry, while a heavier pot suggests there is still sufficient moisture within. Visually, the very tips of our new, soft growth may begin to droop slightly when we are under-watered, but this is a later sign and should not be relied upon exclusively.
Our watering frequency is not static; it changes with our conditions. During the active growing season (spring and summer), with longer days and more intense light, we are metabolizing water faster and will require more frequent watering, perhaps once a week or so. In the dormant winter period, with lower light levels and cooler temperatures, our water needs drop dramatically, and you may only need to water us every two to three weeks. Other factors include the size of the pot (small pots dry out faster), the type of potting mix (a coarse, bark-based mix drains faster than a peat-heavy one), and the humidity and airflow in the room.
When it is time to water, do so properly. Take us to a sink or basin and slowly pour room-temperature water over the soil until you see it running freely out of the drainage holes at the bottom of the pot. This ensures the entire root ball has been evenly moistened. It is crucial that you allow all excess water to drain away completely before placing us back into our decorative pot or saucer. Never let our pot stand in a tray of water.
