Deadheading roses is common practice and is easy. The same method applies to Knockout Roses as well as Bush, Climbing and Standard types.
Why Deadhead Roses
Their are a few reasons to prune back the dead flower heads on roses.
By removing the spent flower heads you encourage the rose to put its energy into creating new flowers rather than producing seed.
What happens when flowering is over is that pollinated flowers produce a hormone that sends a message to the plant, and the message is ‘we are now going to produce seed’. This is not what we want.
This is only true for the repeat flowering types, and if you want rose hips for their decorative value, them you will not deadhead at all.
It also tidies up the plant, so the garden looks better.
How to Deadhead Roses including Knockout Roses
Roses are a little different to other plants, it’s not simply a matter of cutting the flower heads off, you need to cut them at the right position.
Look for a leaf below the flower that has five leaflets on it and prune to this.
You should look for an outward facing leaflet to deadhead to. This just tends to keep the rose more open. If you can’t find one do not worry.
Make the stem of the rose is of a good thickness, at least the same a pencil. If the stems are thiner the new growth tends to be too heavy for the stem.
The further down the stem you cut the stronger the canes but the fewer the flowers.
Forget the concept of just pinching off the flower head, this is a short term measure.
In our example pictured right you can see a few of the main points illustrated.
From the top down
- The spent flower head ready for deadheading.
- Below this. two sets of leaves with only three leaflets on each.
- Next is a leaf with five leaflets, however the stem is a little too thin.
- Below this we have two sets of leaves with five leaflets and a thicker stem. Deadhead to either of these.
- The cut is made on an angle just above where the leaf meets the stem. Remember to slope the cut.
You can deadhead any time from the first flowers to about 4 weeks before the first frosts usually hit you zone. After this you should leave them until spring.
A few things to do after deadheading
- Dispose of the old flower heads, do not compost them.
- Give you roses a light feed with a specialist rose fertilizer.
- Water them well.