Deadheading is key to the garden’s performance, particularly in late summer, August/Sept. Deadheading is simply the removal of the spent blooms in the garden. By mid or late August, typically the lavender is due to be sheared back to the foliage. Dahlias are in full swing, but like most perennials, will nearly stop blooming if the dead flowers are not cut off. Plants such as Leucanthemum have spent flowers that are not attractive, and need to be cut back. And so it goes.
So though there are these tasks and many more in August, there are also rewards. If you deadheaded your garden in June and July, your roses are still in full swing. If you cut back salvia and centranthus, it is now entering the second round of blooming. If you have kept your pelargoniums (such as the red “geraniums”) deadheaded, they are now larger plants yielding many more flowers than early in the season. Without deadheading these plants you will have a lot of nothing in August.
Deadheading is the mark of the gardener. Weeding, Watering, Deadheading. Those are the tasks. When you see a well tended garden, it is a lovely sight. Only deadheading takes a bit of confidence. To deadhead, you have to actually cut on a desirable plant (a minor form of pruning). Many newer gardeners are reluctant at first. As Nike says, just do it.
Some deadheading you can simply beat to the punch. When a hosta starts to bloom, cut off the scape. These are shade plants and the blooms are not key to them and they really become ratty looking left untended. Cleaning them up in the garden takes but a few minutes, but those are well spent. Ditto for most heucheras, though we do offer one or two ornamental heucheras that have kept their attractive coral bell flowers of days past.
Roses may even have buds removed. Removing 1/4 or so of the buds when they appear will often promote more continuous blooming. Definitely there is a big improvement just by removing the spent rose blossoms. Check out the photo of the Drift rose hedge taken in mid-August. It is simply covered in bloom.
Deadheading is the most critical task, but you can also groom plants by removing damaged leaves, improve their form, and so forth. So long as the pruners are in your hand, use them.
I really suggest having a holster for your pruners and wearing them when you go into the garden. If the tool is right there on your belt, when you see a spent blossom it takes but a second to take it off.
Finally, yes there are plants that do not require deadheading. But most (Iris, Peony, Daylilies, Lavender, Daisies, etc) leave unattractive bits after their bloom and it is up to you to take them off. The modern petunias are self cleaning, Geranium ‘Rozanne’, Delospermas, Junipers and most evergreen plants, Oenothera macrocarpa, most grasses, Zauschnerias, and so on do not require deadheading, though a garden composed only of these would be lacking some elements. When I design a garden, I try to adjust what is installed to the care it will receive. But the reality is that some deadheading will always improve the garden.
So strap on the pruners and spend an hour in the garden. Cut off those spent yucca stalks, the hosta flowers, the dead blooms on the zonal geraniums and so forth. You’ll be amazed how much that hour will improve the look of the garden, as well as enhance performance in the coming month.