I have 2 Kentia palms in a conservatory. They are about 5-6 ft in height. They are in pots which have a water reservoir that you top up when the water level gets low. The leaves have started to go completely brown and shrivel. This has affected both plants and has happened to almost all of the leaves. I have read articles and books but don't know whether the plant is too dry or too wet or what the problem is. Can you help please?
Kentia palms need very well draining soil. If overwatered the roots could rot. You will need to determine if the soil is too wet.
If it feels wet and soggy they are over watered.
I would inspect them carefully for any signs of bugs or disease.
Here are a few links to help you pinpoint the cause.