Verbena cutback
QShould I cut back Verbena bonariensis in autumn or leave for the spring? Lucy Hutchinson, via email
AI suggest that, if you don’t mind viewing its tall, dead stems over winter, you leave your Verbena bonariensis to harbour and protect tiny insects from the cold.
Then, in April, when new shoots are sprouting from the base, cut back the stark stems to within 4in (10cm) of the base. It is also a good time to feed it with fish, blood and bone meal, processed seaweed or some other soil-benefiting organic fertiliser to speed robust growth.