Yellow foliage can result from too much water, drought, root damage, nutrient limits, pests, disease, low light, cold, or normal aging. Fertilizer helps only some of these. Read the pattern before adding a product.
1. Which leaves yellow first?
Older lower leaves fading evenly can mean normal replacement or a mobile-nutrient shortage. Yellowing in the newest leaves can point to unavailable micronutrients, root-zone pH, or damaged roots. One shaded interior leaf matters less than the same pattern across many growing tips.
2. What pattern appears on each leaf?
Uniform pale color differs from green veins with yellow tissue between. Brown margins, bleached patches, defined spots, and fine stippling are separate clues. Photograph both sides of a typical leaf in natural light and compare progression over several days.
3. What is happening around the roots?
Check moisture below the surface. Constantly wet soil limits oxygen, while a dry root ball may repel water so irrigation runs around it. In containers, make sure drainage holes are open and the pot is not standing in collected water unless the species requires it.
4. What changed?
Consider transplanting, heat, cold nights, construction, herbicide drift, new watering, root disturbance, repotting, or different light. Symptoms starting soon after a change are often connected to it.
5. Are pests or disease signs present?
Inspect leaf undersides, stems, buds, and the boundary between healthy and damaged tissue for webbing, scale, insects, sticky residue, distorted growth, fungal structures, or lesions.
Decide before treating
Correct obvious water, drainage, or light problems and allow recovery time. Test soil when a persistent nutrient or pH issue is plausible, especially before applying lime or fertilizer. For a valuable tree, rapid spread, or possible chemical injury, contact a local extension service or qualified plant professional with photos and site history.