Broom trouble (Cytisus)

They ARE hardy plants for temperate zones, but if yours was only just planted last year, perhaps it hadn't set out enough roots to be ready for extremes. A few hybrids such as "Lilac Time" & any that are semi-dwarf are a bit more sensitive.

Usually even after winter damage brooms can be hard-pruned & will regrow, even if cut flush to the ground, but their first couple seasons in the ground in "the usual" droughty locations may leave them weak for needing to be watered their first summer. Conversely, too regular of watering their first year can sometimes cause black rootrot.

Though not generally susceptible to disease there certainly are exceptions. They're attacked by peach scale & can be killed by leaf blight, & in a few areas of the west coast a broom-killing twig-mining moth has been turned loose as a biological control for invasive wild broom. But these moths kill garden hybrids too.

My brooms: