Plant Problem Diagnostic
Why Is My Indoor Citrus Tree Dropping Leaves and Yellowing?
The short answer
Yellowing and leaf drop on a potted citrus most often comes down to overwatering: when the soil stays wet, the roots can't function, so leaves yellow and fall. But it could also be too little light, cold or drafty conditions, a recent move, or a nitrogen shortage, so rule out the obvious first.
Check the soil moisture two inches down before watering, make sure the tree gets at least six hours of direct light (a south or southwest window), and avoid abrupt temperature swings. Some drop after moving a tree between indoors and out is a normal adjustment. If yellowing keeps spreading after you correct water and light, your local Extension office or Master Gardener program can help diagnose.
Start with water and roots
Overwatering is the leading cause of yellow citrus leaves. When soil stays continually wet, the roots can't take up nutrients, so leaves turn yellow and may drop. Cold soil has the same effect: chilly, soggy roots stop working and the tree yellows even though it isn't short of water.
Before watering, press a finger two inches into the soil; if it feels dry, water, and if it's still damp, wait. Wisconsin Horticulture notes that cupped or yellowed leaves can be a symptom of excessive watering, and advises watering infrequently but deeply and cutting back in winter when growth slows. If the tree is yellowing and the soil is wet, do not water more.
Light, cold, and sudden change
Indoor citrus needs a lot of light. Wisconsin Horticulture recommends at least six hours of direct light daily from a south or southwest facing window; without it, leaves pale and the tree struggles. Citrus does best between about 55 and 85 degrees Fahrenheit, so keep it away from cold drafts and hot heating vents.
Sudden change is a classic trigger for leaf drop. Moving a tree from low indoor light straight into full sun, or vice versa, can make leaves, flowers, and young fruit drop as the plant reacts. When you move citrus indoors for winter or back out in spring, do it gradually so it can acclimate, and expect a little drop as normal.
Nutrients, and when to look closer
Citrus are heavy feeders, and yellowing leaves may simply mean the tree needs more fertilizer, particularly nitrogen. But feed only when water and light are right, because pouring fertilizer on a cold, overwatered tree won't green it up and can make salt buildup worse.
Because overwatering, cold, light, and nutrients all produce similar yellowing, don't assume it's one thing; check them together. If you can't tell what's driving it, or if the tree keeps declining after you've corrected the basics, send photos to your local Extension office or Master Gardener program. For general potted-citrus care, see our guide on how to grow a lemon tree in a pot.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Wisconsin Horticulture (UW-Madison Extension) - Indoor Citrus — States indoor citrus needs at least six hours of direct light daily from a south or southwest window, thrives between 55 and 85 degrees F, that cupped or yellowed leaves can be a symptom of excessive watering (keep soil moist but not wet, water deeply and infrequently, reduce in winter), that yellowing leaves may indicate a need for more fertilizer, and that abrupt changes such as moving from low light to full sun can cause leaves, flowers, and young fruit to drop.
- UC Agriculture & Natural Resources (Alameda County Master Gardeners) - Yellowing Leaves and Leaf Drop in Citrus in Winter — Explains that overwatering is a common cause of yellow citrus leaves because roots in continually wet soil cannot take up nutrients, and that cold temperatures cause transient root dysfunction and yellowing in winter that resolves as the weather and soil warm.