Q.The Leaves On My Citronella Plant Are Turning Brown. What Would Be The Cause?
I recently purchased two citronella plants from Home Depot and one of them has started turning brown at the leaves. I water it once a day and I do have it out in the sun. Could it be that there is too much sun or too much water. I have uploaded pictures.

Certified GKH Gardening Expert
I would cut back on the watering and see if that helps. You don't need to water it every day. Let the soil dry out between waterings. When grown outside, it is fairly drought tolerant. Also, check the drainage. Do the pots have several drainage holes? Geraniums don't like wet feet. If water is not draining well, that could be a death sentence.
They like about 6 hours of sun a day, so it probably isn't getting too much.
Here is more care information.
https://www.gardeningknowhow.com/edible/herbs/scented-geranium/mosquito-plant-pruning.htm