  The theory of massive gravity proposed by Bergshoeff, Hohm and Townsend is
considered in the special case of the pure irreducibly fourth order quadratic
Lagrangian. It is shown that the asymptotically locally flat black holes of
this theory can be consistently deformed to "black flowers" that are no longer
spherically symmetric. Moreover, we construct radiating spacetimes settling
down to these black flowers in the far future. The generic case can be shown to
fit within a relaxed set of asymptotic conditions as compared to the ones of
general relativity at null infinity, while the asymptotic symmetries remain the
same. Conserved charges as surface integrals at null infinity are constructed
following a covariant approach, and their algebra represents BMS$_{3}$, but
without central extensions. For solutions possessing an event horizon, we
derive the first law of thermodynamics from these surface integrals.
