Why are the lower leaves of my houseplant turning bright yellow?

What's likely going on

From the photo, the lower leaves are turning a solid bright yellow, while the newer, upper leaves are still deep green. There are no obvious spots or bite marks, so this doesn’t look like pests or a leaf disease.

That pattern usually means one (or a mix) of:

1. Normal aging plus low light: Oldest leaves naturally yellow and drop first, especially if the plant isn’t getting quite enough light to support all of them.
2. Over‑watering or poor drainage: If the soil stays wet for days or the pot sits in water on the saucer, roots get starved of air and older leaves turn yellow and limp.
3. Under‑watering (less likely here): If the soil becomes very dry and the leaves feel crispy, they can also yellow, but the whole plant usually looks droopy.

Without touching the soil it’s hard to be exact, so checking the pot and soil moisture is the key to telling these apart.

What to do

1. Check the soil and roots. Push a finger 2–3 cm into the soil. If it’s soggy or smells sour, it’s staying too wet. If it’s bone dry and pulling from the sides of the pot, it’s too dry.
2. Fix drainage. Make sure the pot has holes at the bottom. Empty any water that collects in the saucer after 10–15 minutes. If there’s no drainage, repot into one with holes using a light, chunky mix (potting soil mixed with perlite or bark works well for most foliage plants).
3. Adjust watering. Water thoroughly only when the top layer of soil feels dry. For most indoor foliage plants, that means letting the top 2–3 cm dry between waterings rather than keeping it constantly wet.
4. Improve the light. Move it closer to a bright window with filtered light, or keep it where it gets bright indirect light for several hours a day. Avoid harsh midday sun right on the leaves.
5. Remove spent leaves. Once a leaf is fully yellow, snip it off close to the stem with clean scissors. This won’t fix the problem but tidies the plant and lets it focus on healthy growth.

How to prevent it

• Keep a simple watering routine: check the soil first, then water; don’t go by the calendar alone.
• Use pots with drainage holes and a well‑draining mix so excess water can escape.
• Give steady bright, indirect light; dim corners lead to more leaf drop.
• Feed lightly with a balanced liquid fertilizer at half strength every 4–6 weeks during the growing season if the plant is actively putting out new leaves.

When to worry

• If many leaves yellow at once, including the newer ones.
• If the plant becomes mushy at the base or the soil smells rotten (signs of root rot).
• If you see tiny insects, webbing, or sticky residue on leaves.

In those cases, unpot the plant to inspect the roots, trim any brown/mushy ones, repot into fresh, airy soil, and reduce watering while it recovers.