Old growth provides winter structure and homes for predators
When I was younger, one of the hard and fast rules was to cut back herbaceous perennials in autumn, leaving a very bleak picture until the new growth in spring. However, things have become a little more enlightened. We think more about the wider ecology of our gardens and less about how tidy we are.
If you are a fanatic about order and can’t stand dead stems in your borders, bear this in mind. You are removing vital homes, habitats and food for wildlife, especially helpful predators that will eat pests next summer.
Winter interest, height and structure
There’s also the lack of winter interest, height and structure. Imagine missing frosted stems in the early morning before you go out to work? If you’re actively looking for winter interest, try the dried flowerheads of teasels, cardoons (Cynara), globe artichokes, Sedum spectabile, Eryngium (sea holly), Phormium (New Zealand flax) and the foliage and flowers of ornamental grasses.
Some of the few plants old-school gardeners left over winter were borderline hardy perennials. These include penstemons, Knifophia (red hot pokers) and ornamental sedges, so the old stems protected the crown from frost.
Cutting back herbaceous perennials in spring
Evergreen perennials such as Kniphofia and ornamental sedges are not cut back but are tidied up during spring and summer by removing dead foliage.
- From March onwards, more care is needed, as new growth will probably have started.
- Using a knife, shears or secateurs, cut stems close to the crown, avoiding the new shoots.
- Tidy up the base of the plant, mulch and feed with a general fertiliser, such as Growmore.
Cutting back early-flowering herbaceous perennials
Perennials and rock plants, such as geraniums (cranesbills), delphiniums and Aubretia, are cut to near ground level after flowering to encourage new foliage and another flush of flowering.
