My brugmansia is dying from it's tips inwards --- it blackens, becomes limp and leathery and dead. Each of these ends has lost a couple inches. I tried surgically amputating a tip to no avail. I hadn't been watering it so I increased the watering and that didn't help either. Admittedly, I don't have any experience with these and maybe this happens every year and in the spring it just starts growing again --- is that what happens?