From our perspective, the most common grievance we express through browning leaf tips is a problem with water. It is a misconception that we are always drought-tolerant. While established Grevilleas prefer infrequent, deep watering, our delicate, shallow feeder roots are highly sensitive. If the soil is consistently waterlogged, these roots suffocate and rot, preventing them from absorbing moisture and nutrients. Ironically, this creates a physiological drought where we are surrounded by water yet dying of thirst, resulting in brown, desiccated-looking leaves. Conversely, extreme and prolonged lack of water will cause simple dehydration, where the leaf tissue dies back from the tips and margins inward.
Our foliage is particularly adept at communicating chemical dissatisfaction. Many Grevillea species are native to nutrient-poor soils and have evolved to be highly efficient at nutrient uptake. Applying a standard, phosphorus-heavy fertilizer is akin to forcing us to consume a toxic substance. This causes a rapid burn, visibly scorching our leaf tips and margins. Similarly, water high in dissolved salts (common in reclaimed or softened water) or a buildup of salts in the soil from fertilizer will create an osmotic imbalance, drawing water out of our root cells and causing a similar burn pattern on our leaves.
Our leaves are the primary interface with the atmosphere, and they bear the brunt of environmental stress. Intense, direct afternoon sun, especially when coupled with reflected heat from walls or pavements, can literally scorch our foliage, causing browning. Harsh, drying winds have a similar effect, accelerating moisture loss from the leaves faster than our roots can replace it, leading to desiccation and tip dieback. Furthermore, a sudden drastic change in our environment, such as being transplanted on a hot, sunny day, can send us into shock, manifesting as widespread leaf browning as we struggle to adapt.
While we are generally resilient, we are not invincible. Sap-sucking pests like spider mites, scale, or aphids attack the undersides of our leaves, puncturing the surface and draining our vital fluids. The damage from their feeding appears as stippling, yellowing, and eventually browning of the leaf tissue. Fungal pathogens, often encouraged by the same waterlogged conditions that cause root rot, can also invade our vascular system or leaf surfaces, blocking the flow of water and causing sections of the plant to wilt and turn brown from the tips back.
