The best way to get a valid diagnosis, is to fill-out the troubleshooting form. It might be a pain in the ass, but without all of your information, any diagnosis will be a guess. All the questions on the form are important in some way or another...so be as thorough as possible.

Just by looking at them...not overnuted and it's not heat stress. But that's as far as I'll go.

Once soil is dry enough, gently and carefully slip the rootball out and see what the roots look like. Should be healthy white roots. If browning and slimy, likely it's either overwatering causing root rot, or you are not letting the soil dry enough between waterings. If only a few white roots in a tangle of dry brown roots...likely underwatering.

Use the troubleshooting form to your advantage. :thumbsup: