welcome to GoY.
it could be one of two things.
the air might be too dry so the tips are shrivelling [try misting them]
or
The leaves exude water over night then they are getting scorched by the sunlight shining on them. [try shielding then from direct sunshine.]

The main culprits for this are too much or too little water. Keep the soil consistently moist but not sopping wet or muddy. A layer of mulch will help. Be sure you have sufficient drainage.

Do you have a water softener, Harold? The sodium in softened water can cause that kind of damage. Also naturally salty water, like we have here in Phoenix.