If you have a large flower bed or border you may sometimes wonder whether the constant deadheading is really worth the effort involved. But if you fail to remove the spent blooms the plant will stop producing new flowers and will divert its energy into making seeds. While deadheading is a simple process there is a right way and a wrong way of dealing with different plants as Claudia De Yong explains in her article which I found on the Houzz website.

When flowers fade they lose their attraction, leaving borders and beds less attractive. Deadheading directs energy into stronger growth and therefore more flowers. I get asked a great deal about why we need to deadhead plants, especially how and when to do it.
Roses

Claudia De Yong Garden Design

When the flowers on roses start to wilt or fade, it is best to deadhead as the petals can damage the leaves. In terms of simple deadheading ? rather than pruning, which is done in late winter or March ? there are two types that can be done on hybrid and floribunda roses.For hybrid roses, which bear one flower on a single stem, cut the flower stems back, which ensures you have a strong stem to support any new blooms. Cut to around 15cm of an out-facing shoot, meaning one where the bud is facing the direction in which you wish the rose to grow, and make an angled cut just above the bud.

Hydrangea

Botanica Atlanta | Landscape Design-Build-Maintain

Depending on the variety of hydrangea, different methods apply. For mopheads and lacecaps, the latter pictured here, you can either deadhead the flowers immediately as they die off or leave them on the plant over the winter months if you don?t mind the blooms becoming dry or turning brown in colour. There is a benefit to leaving them on until the following spring ? it will help to protect the new season?s growth against frost. Come spring, you can chop them off: in this instance, cut back the spent flower to the nearest bud on the stem below.

 
Rhododendrons and Azaleas, Camellias and Lilacs

Proven Winners

With Azaleas and Rhododendrons, you can snap off the spent flower truss (which is the same as a cluster) after flowering, but be careful not to damage the new young growth coming through underneath. Some of the plants in your garden may be too big to do this to as they can grow to huge proportions. If that is the case, I suggest you do this with your younger plants and any parts of the larger ones you can reach easily. If you don?t deadhead these shrubs, the plant will waste all its energy into making big fat seedpods, inhibiting growth and so limiting any flowering the following season.