I would say you are over watering. You may have a case of early root rot and it is spreading to the bottom of the stem and through a weak system of water uptake from it the tops are not getting water and drying out.
Let your soil, if you are using soil, get almost dry before watering and then lightly water. You would be better to not water so often and in smaller amounts than to soak the soil.
Many newer growers kill their plants with kindness by giving them to much water and to many nutrients to often. Of course both are needed to maximize your yield but remember that pot is basically a weed and can and will grow in harsh conditions and still do well so it is not like it needs to be totally babied and watered and or fed daily. Let them dry out and then just get them moist and then let them get close to being dry again and then do the moist thing again and don’t soak them and don’t let your pots sit in water so it keeps soaking it up into the soil keeping it highly saturated all the time. Pour off any runoff/run through and let things dry out some.
You will be far more likely to kill them by over watering them than by under watering them. If you under water them and they get droopy and then give them some water unless you totally dried them out about 99.9% of the time they will spring right back but if you over water them and they get root rot that’s a real problem
While letting the soil dry out you may want to take a spray bottle and spray the leaves that look a little dry and maybe they will absorb some of the moisture and not die and drop off or at least fewer will.
thx
