Leaves on my indoor plants- Why do the leaves turn dark and brittle?

How old is the plant? When are you watering?Are you testing the soil before watering?

Air is probably too dry/...........

Not enough water. Water from the bottom.

Is that a heat register behind that plant? Could be it is drying out from where you have it sitting. Place it next to the thriving one and treat them the same! The observe if there is any change.

Sounds like it needs to be re-potted in fresh soil and make sure the container has drainage holes.

Is it against a cold wall? That happened when my plant got frostbite..

Try misting the plant using a small spray bottle. A lot of our indoor plants are tropical in nature and need the topical moisture.

Look up your type of plant for watering, light and fertilizer. All needed for living things. Insects or desease may be a problem also. I would remove from pot, rinse with light soapy water and repot; then follow your information for light,food and water! Mary

Definitely look up the type of plant. Each one is different in needs for light and water. Looks kind of like a peace lily, but hard to tell from the photo. If it is a peace lily, I learned they need very little water, like only about 1/2 cup each week. Mine did much better when I reduced watering. But make sure what plant you have — that’s the key!

Do you have a water softener? If so, it could be salt build up in the soil. Plants are very sensitive to that.

1000% agree with Jeanette, it’s the floor register. Move the plant. The leaf is burnt and dried out.

I agree with the floor register, it is drying out the leaves. Look up the type plant and see what it says about the moisture it likes, some like to dry out between watering, some like to stay somewhat moist all the time. Being so close to the register it is probably drying out quicker than the other plant. Purchase and use a moisture meter to make sure it is getting enough moisture and keep the leaves from the hot air coming out of the register.

I have this same plant - it does like sunlight. Does it have good drainage in the pot or did you add rocks to the bottom of the pot before planting? Don't over water this plant, just once a week - touch the soil and if dry water.