Yellow leaves on a houseplant are one of the most common problems, and also one of the most frustratingly non-specific symptoms, overwatering, underwatering, too little light, nutrient deficiency, root rot, natural ageing, and pest damage can all produce yellow leaves.
This guide covers the most common causes of yellow leaves on houseplants, how to tell them apart, and what to do in each case.
Overwatering
Overwatering is the single most common cause of yellow houseplant leaves in the UK, and it is frequently misdiagnosed as underwatering because the symptoms can look similar. Overwatered plants typically show yellowing that begins in the lower, older leaves and progresses upward. The yellowing is often uniform: the whole leaf changes colour rather than browning at the edges first. The compost is consistently wet when you check it, even if it has been several days since you last watered.
The underlying mechanism is root rot caused by permanently saturated compost: waterlogged roots cannot absorb nutrients efficiently, which produces the same nutrient-deficiency symptoms as starvation even when nutrients are present in the soil. If you remove the plant and check the roots, overwatered roots are brown, mushy, and may smell sour or unpleasant rather than the firm, white or pale tan of healthy roots.
To treat: allow the compost to dry out significantly between waterings. If root rot is present, remove affected roots, dust cut ends with cinnamon, and repot into fresh, free-draining mix. See our guide to how often to water houseplants for a reliable method for judging when your plant actually needs water.
Underwatering
Underwatering can also cause yellowing, but it typically presents differently from overwatering. An underwatered plant usually shows wilting or drooping first, with yellowing appearing later if the drought is prolonged. The leaf edges and tips tend to go brown and crispy before the rest of the leaf yellows. The compost is bone dry and pulls away from the sides of the pot. The plant is noticeably lighter than a recently-watered equivalent.
The fix is straightforward: water thoroughly, ideally with a bottom soak for 20 to 30 minutes if the compost has become very dry and hydrophobic, and the plant will usually recover within a few hours if the drought has not been extreme.
Natural Leaf Shedding
The lower, oldest leaves on most houseplants yellow and drop as a normal part of the plant's life cycle. This is not a cause for concern and does not indicate a problem, provided new growth is appearing at the top of the plant and only the oldest lowest leaves are affected. A Pothos dropping one or two older leaves a month, a Monstera yellowing its lowest leaf, or a Dracaena slowly losing its lower fronds over time are all entirely normal.
The key distinguishing feature of normal shedding is that it affects only the oldest lowest leaves, one or two at a time, while the plant continues to produce healthy new growth at its growing tip. If yellowing is spreading upward rapidly or affecting new leaves, It isn't normal shedding.
Too Little Light
Light-stressed plants slowly yellowing their older leaves is a common pattern in UK winters and in rooms with poor light. Low light reduces photosynthesis, which means the plant cannot maintain all its leaves efficiently. It prioritises the newest growth by drawing nutrients from the older leaves, which turn yellow before dropping. The pattern is similar to normal ageing but progresses faster and may affect more leaves simultaneously.
The fix is more light: move the plant closer to a window, or add supplemental lighting. Our guide to grow lights for houseplants explains what to look for when choosing a grow light, and our guide to low light houseplants lists the species that cope best without supplemental lighting.
Nutrient Deficiency
Nutrient-deficient plants often show yellowing in a characteristic pattern that depends on which nutrient is lacking. Nitrogen deficiency (the most common) produces uniform yellowing of older leaves first, as the plant mobilises nitrogen from older tissue to support new growth. Iron or magnesium deficiency typically produces interveinal chlorosis, the leaf blade yellows while the veins remain green, usually in newer leaves first.
Before treating a suspected nutrient deficiency, rule out overwatering and root rot. Root damage from overwatering produces identical symptoms to nutrient deficiency because damaged roots cannot absorb nutrients even when they are present. If the compost and roots are healthy, feeding with a balanced liquid fertiliser during the growing season will address most deficiencies within a few weeks. See our guide to when to fertilise houseplants for a feeding schedule. BioBizz Bio-Grow is a reliable organic liquid feed that covers the main macro and micronutrients without the risk of over-application that comes with concentrated synthetic feeds.
Pest Damage
Spider mites, thrips, and mealybugs can all cause yellowing, typically accompanied by other visible signs, stippling or silvery speckling from spider mites, bronze streaks from thrips, white cottony deposits from mealybugs. If yellowing is accompanied by any of these visible signs, treat for pests first and reassess once the infestation is cleared. See our full guide to common houseplant pests for identification and treatment of each.