Unlike trees, a shrub can easily survive the lopping of its stems. Pruning stimulates growth and increases the vigour and productiveness of the plant.
To a plant, pruning is a stimulus. Although you have reduced its size by cutting it back, you stimulate the growth of buds on the plant that were once forced to be dormant by the dominance of the terminal bud.
Remove the bud and others below will start to grow resulting in a bushier plant.
What does pruning actually do?
Gardeners talk a lot of rot about pruning. They talk about all the plant’s energy being routed into certain directions and whereas this might be the end result, what is actually going on is the result of changes of hormone levels within the plant.
Each bud, and the tip of each branch, as well as each flower, and in the roots too – as well as under the bark and deep in the branch, gives off a cocktail of hormones that determine how the plant will grow. If you remove a branch, the hormones produced by it are removed, and this has consequences for the rest of the plant.
So, if you cut the branch off just above a bud, the hormones from that branch that usually inhibit the bud from growing are suddenly removed, and the bud will start to grow!
Pruning can allow us to create a plant that will grow in a way we want it to, rather than how the plant might naturally wish to grow. And there are many advantages to this. You have to remember that a bud will grow in the direction it is pointing and therefore you can determine the overall shape of the plant.
For roses, one of the reasons for pruning is to cut down the amount of fungal problems by allowing the breeze to flow through the plant effectively. This is done by creating a plant that is goblet shaped.
When you are pruning you need to look. Which way is the bud you are cutting above pointing? if it is towards the inside of the plant, then choose another that points outwards.
Read part two – the practicalities of pruning.
Paul Peacock studied botany at Leeds University, has been the editor of Home Farmer magazine, and now hosts the City Cottage online magazine. An experienced gardener himself, his expertise lies in the world of the edible garden. If it clucks, quacks or buzzes, Paul is keenly interested.
He is perhaps best known as Mr Digwell, the cartoon gardener featured in The Daily Mirror since the 1950s. As Mr Digwell he has just published his book, A Year in The Garden. You can also see more about him on our Mr Digwell information page.