If you want to grow shrubs in the garden of your dreams, but also wish to include drifts of perennials as a follower of the latest trends in naturalistic planting, you will quickly hit a problem that I have struggled with for a long time.
This picture of a wonderful Hydrangea aspera ‘Villosa Group’ taken this afternoon in my small garden will hopefully illustrate the problem.
I planted this shrub three years ago hard up against the fence which offers it shade during the hottest part of the day; it has thrived. The small border surrounding it was filled with a mixed planting of epimediums, astilbes and autumn flowering anemones; a miniature perennial meadow in fact.
As you can see the hydrangea has spread forwards and sideways and swamped a major part of its surrounding neighbours. I now have two choices: either I must intervene and prune the hydrangea or leave things to take their course and accept that the shrub is eventually going to take over this whole border.
Probably, I am going to take a middle course by lightly pruning next spring in order to keep the hydrangea at about the same size and prevent it from spreading out over the path. But by including a shrub in this mixed perennial meadow planting scheme I have created a problem for myself and thereby added to my workload.
In the normal process of maturation, vegetation moves steadily forward from pioneering species on disturbed ground to eventually becoming closed woodland; shrubs and trees will eventually eliminate the herbaceous plants at ground level. As gardeners it is this process that we attempt to temper, but in truth our efforts are doomed.
However, I am not going to stop adding trees and shrubs to my gardens simply because I want to grow wide drifts of perennials. I must accept that when I introduce them that I am going to have to play an active role in maintaining the balance.
Current trends in perennial planting favour wide drifts of meadow-like schemes in which we can enter and become overwhelmed by the abundance of flower and vegetation. Their scale is larger then traditional herbaceous or mixed borders and as such we need to minimise the time and effort needed to maintain them. It is for this reason that I have concluded that I should aim to plant the shrubs and the perennials in my gardens in separate borders. By separating these plants into distinct zones I can efficiently manage each as needed, the competition between them is under control and the schemes become more durable.
Simply by having a path with shrubs on one side and a meadow border on the other you gain the control that any mixed scheme looses. Naturally there are going to be occasions when you decide to break the rule, but you do so in the knowledge that you have created a battle field and you will have to work at it to keep things in the manner intended.
The New Perennial Movement fails when the schemes created under its banner lack clear, year round structure, and shrubs are, in my opinion, one of the best ways of introducing it. However, I am not advocating trim yew and box hedging, rather a more diverse arrangement of strategically place shrubs to bring focus and form to the planting areas. I will have to see if I can find some examples to illustrate my next post on this subject!