Should you prune perennials or not? There is no blanket yes or no, but two tips that will help with the decision.
Some say perennials must be pruned, others advise against it. In general, you can do whatever you want in your garden, but a reasonable pruning makes sense for most perennials. On the one hand, this prevents uncontrolled proliferation and, on the other hand, promotes the second flowering phase. You should keep these two tips in mind when pruning the perennials.
❶ Cut perennials in summer
When perennials have withered, you can confidently cut them. On the one hand, this strengthens the perennials, on the other hand, they usually sprout again and form a second flower. In addition, the pruning prevents self-seeding. Begin summer pruning once most of the blooms have faded. Cut about a hand's breadth above the ground. Then give the perennial some fertilizer and water it to encourage new growth of the shoots. Such perennials are, for example, delphinium, foxglove or cranesbill.
To avoid radical deforestation in the garden, do not prune some perennials at all. Candytuft, pampas grass, hazel root or cherry laurel, for example, can remain.
❷ Cut perennials in spring - stay away in winter
Stop pruning perennials before winter. The withered shoots simply remain. This offers the plant additional protection in the cold season and usually doesn't look too bad. Such perennials are plants that bloom into autumn, such as liatris, monkshood, fat hen or asters and chrysanthemums. The cut then takes place in the spring.
If you still want to cut in autumn, you are welcome to do so, but then the plants are more susceptible to frost damage. It is therefore best to cover it well with leaves, but then remove it again in good time in spring to avoid rotting.