Perennials

Perennials are hardy plants that die back above ground in autumn and regrow from their rootstock in spring. You will find classics such as peonies, phlox, daylilies and hostas as well as hardy geraniums, speedwell and Japanese anemones. Plant them in spring from March to May or in autumn from September to October.

Buy hardy perennials: choosing by location

The most important step in choosing perennials is the location. Perennials suited to the light and soil grow strongly, flower generously and need little care for years.

Perennials for sunny borders

In full sun you can grow peonies, which bear large, often fragrant flowers in May and June, along with phlox and daylilies (Hemerocallis) for high summer. Perennial salvia and speedwell (Veronica) form blue and violet flower spikes that bees love. For dry spots, choose oriental poppies (Papaver), sedum and sea holly.

Perennials for partial shade and shade

Under trees and on the north side of the house, foliage perennials come into their own. Hostas come with green, blue and variegated leaves, while astilbes flower in white, pink and red in moist partial shade. From August, Japanese anemones add colour. Foxgloves, columbines and bergenias complete shady planting schemes.

Ground cover and gap fillers

The hardy geranium is one of the most versatile perennials. Varieties such as 'Rozanne' flower from June into autumn and keep weeds down. Lady's mantle and bellflowers suit the edges of borders and go well with roses.

Planting time and planting in Switzerland

On the Swiss Plateau, perennials are best planted from March to May or from September to October. Autumn planting has the advantage that the roots establish before spring. At higher altitudes, spring is the safer choice. Loosen the soil to a spade's depth, remove perennial weeds and work in some well-rotted compost. Plant at the same depth as in the pot and water thoroughly.

• Spacing: low perennials 25 to 30 cm, medium-height ones 40 to 50 cm, tall perennials such as peonies 60 to 80 cm.
• Groups: three to five plants of the same variety look calmer than many single plants.
• Care: water regularly in the first year, later only during long dry spells.
• Cutting back: leave dead stems until late winter, as they give insects somewhere to overwinter.
• Feeding: a thin layer of compost in spring is enough for most species; showy perennials such as phlox and peonies benefit from some organic fertiliser.
• Dividing: divide many perennials every three to five years in spring or autumn, but leave peonies undisturbed where possible.