To understand our needs, you must first understand our origins. Many Grevillea species, like the popular 'Robyn Gordon' or 'Canberra Gem', hail from Australia. Our native environment is not one of constant, oppressive humidity, but rather one of well-drained soils, good air circulation, and periods of dry heat interspersed with rain. Our leaves are often tough, leathery, or finely divided, adaptations that reduce water loss. However, when placed in an artificially dry environment, such as a home with constant air conditioning or heating, the humidity can drop to levels far below what we experience even in our driest native habitats. This prolonged low humidity is a significant stressor.
We will communicate our discomfort, but you must learn to read our signs. The most common symptom of low humidity is browning leaf tips and edges. This starts subtly but can spread, making our foliage look scorched and unattractive. You may also notice leaves becoming crispy to the touch or dropping prematurely. In severe cases, flower buds may abort before opening, or new growth may emerge stunted and weak. This is because when the air is too dry, we lose water through our leaves (transpiration) faster than our roots can absorb it, leading to desiccation of our tender tissues.
One of the most effective and natural ways to increase local humidity is to place us near other plants. Through our natural process of transpiration, each leaf releases minute amounts of water vapor into the immediate air. When grouped together, we create our own humid microclimate, a small zone where the air moisture is higher than in the rest of the room. This is a communal effort that benefits all plants involved. Ensure we are not overcrowded, as this can hinder air circulation and lead to potential fungal issues.
A simple and passive method to assist us is the use of a pebble tray. Fill a shallow tray or saucer with a layer of small pebbles or gravel. Add water to the tray until it is just below the top of the pebbles. Then, place our pot on top of the pebbles, ensuring the base of the pot is not sitting directly in the water (which would cause root rot). As the water in the tray slowly evaporates, it increases the humidity in the immediate vicinity of our foliage. This mimics the moist ground after a light rain, providing us with consistent, gentle moisture from below.
A light, fine misting of water on our leaves can provide temporary relief from dry air. It is a quick way to raise humidity levels directly around us for a short period. However, this should be done in the morning so that any water droplets on our leaves have time to evaporate before evening. It is crucial that we are not left with wet foliage overnight, as this can encourage fungal diseases. Furthermore, while we appreciate increased humidity, we still require good air movement. A gentle breeze from an oscillating fan on a low setting helps strengthen our stems and prevents the stagnant, moist air that pathogens love.
