What to Deadhead
Although not an exact science, there are a few guidelines:
- Large flowers, such as those of some pelargoniums, can be snapped off
individually. The soft stems of most perennials are easily pinched
- If the tall flowering stems of delphiniums, lupines, and foxgloves
(Digitalis) are cut off, new smaller heads might sprout lower down.
- Dainty plants with small flowers such as lobelias are best trimmed
- For repeat-flowering roses, cut off blooms with pruners at the cluster
point, either one by one, or just above a leaf.
An easy way to deadhead some plants is to trim them back with shears.
Trim after flowering for more flowers, fresh foliage, or both. Try this
with border campanulas, catmint (Nepeta), hardy geraniums, knapweeds
(Centaurea), border salvias, and pulmonarias.
In early spring, shear back growth of winter-flowering heathers (Erica carnea), ling (Calluna), periwinkles (Vinca), St. John’s-wort (Hypericum calycinum), and ornamental grasses, taking care not to cut into the new shoots. Also shear off old leaves on epimediums in late winter, before they flower. Cosmos will bloom almost continuously throughout summer and up to the first frost if you continue to deadhead it. Take the long flower stems back to the ferny foliage below.
Leave to Seed
Not all plants need deadheading. Some will not produce more flowers, and
may develop seedheads if flowers are left in place. These may be very
attractive, especially in winter, and the scattered seed could result in
a crop of seedlings the next year. Try leaving the flowerheads on the
- Clematis like C. tangutica, C. orientalis, and their hybrids
- Ornamental grasses