From our perspective as Grevillea plants, we are resilient, sun-loving specimens adapted to well-drained, often nutrient-poor soils. Our roots are designed to seek out moisture efficiently, but they are not equipped to handle constant saturation. When you over-love us with too much water, it creates a crisis in our underground world. Here is what that experience is like for us and how you can help us recover.
We cannot speak, so we communicate our distress through our foliage and overall demeanor. Please learn to read these signs. The first and most critical symptom is yellowing leaves, particularly the older ones. This is not a sign of vibrancy; it is a sign of suffocation. Soggy soil fills the air pockets, starving our roots of oxygen. This prevents us from taking up vital nutrients, leading to chlorosis (yellowing). Our leaves may also become soft, limp, and wilted—paradoxically, they wilt because the roots are rotting and cannot transport water upwards, even though the soil is wet. In advanced cases, you might notice black spots or lesions on the leaves and stems, which indicate fungal infections like root rot taking hold. This is a severe medical emergency for us. Finally, if the conditions do not change, our new growth will be stunted and weak, and we will eventually drop our leaves and flowers in a desperate attempt to conserve energy.
The real damage is hidden from your view, occurring in the root zone. Healthy roots are firm and white or light brown. When forced to sit in water, they begin to decay, turning mushy, slimy, and dark brown or black. This root rot is often caused by opportunistic soil-borne fungi like Phytophthora or Pythium. These pathogens thrive in the anaerobic (oxygen-less) environment you have created. As our root system is destroyed, its ability to absorb water and nutrients is severely compromised. This is why we show signs of drought (wilting) while standing in wet soil—the plumbing system we rely on has been destroyed from within.
If you catch the signs early, you can help us make a full recovery. Your immediate action is crucial. First, stop watering immediately. Allow the soil to dry out significantly. For potted Grevilleas, this is the time to check if the pot has adequate drainage holes. Second, improve soil drainage around our roots. Gently aerate the soil with a hand fork to create air channels, being careful not to damage our already stressed roots. For severe cases, particularly with potted plants, you may need to gently remove us from the pot, wash off the soggy soil, and use sterile pruning shears to carefully cut away any black, mushy, or obviously dead roots. Repot us into a fresh, very well-draining native plant mix, ideally in a terracotta pot which breathes better than plastic.
To ensure this doesn't happen again, you must adjust your care routine to match our natural preferences. Always check the soil moisture before watering. Push your finger 2-3 inches into the soil; if it feels damp, do not water. We prefer deep, infrequent watering that mimics a good rain shower, followed by a period of drought for the soil to dry out. Ensure we are planted in a location with excellent drainage, preferably on a slight slope or in a raised bed. A layer of gravel or mulch around our base can help, but keep it away from the main stem to prevent collar rot. Finally, avoid using rich, water-retentive potting mixes or fertilizers high in phosphorus, which are toxic to us.
