Drought and wind burn. I don't know just where you live but many of us have experienced low rainfall and strong winds since the winter ended.

One of mine is doing the same - the soil was really dry around the roots, so have been watering and feeding well. Not seeing any signs of regrowth yet...

Agree with Bulbaholic, these hate winds and drought.
I'd love to grow them here but the aforementioned means i'll never be able to :-((

I learnt my lesson last year when I experienced the same thing. This year I have kept the potted ones in semi-shade and well protected from the winds which are quite strong... and cold...again...today!