What I am about to write a lot of you will disagree with. In truth, what I am about to recommend is a rule I regularly break, but I do so in the full knowledge of the consequences.
Keep shrubs out of your perennial borders, they create more problems than they solve.
There, I have said it and of course you don’t agree with me; after all wasn’t the mixed border the mainstay of the domestic garden in the second half of the twentieth century.
As a botanical student I learned how plant communities evolved – pioneering species tame a habitat and make it possible for slower growing, more complex communities of plants to establish themselves and ultimately trees grow up to create the habitat’s climax vegetation. Of course it is more complex than this with many possible outcomes but fundamentally woodland is the direction plant communities are moving towards. Along this journey perennials, shrubs and trees (to keep this simple) coexist in a dynamic relationship with one another; given the chance one of them will take over at the expense of the other.
As gardeners we intervene in the nature we nurture to create an environment we find comfortable and attractive. Few of us want to allow the back garden to turn into a forest, so we remove tree seedlings, cut back shrubs and leave openings to allow sunlight in, in order to grow the flowers and vegetables that we desire.
Turning back to my desire to create perennial meadows I am sure you can see the conflict looming between the sun-loving plants I want to favor and the shrubs and trees I also need to use in designing my garden’s landscape.
I have used shrubs, roses amongst them, within my perennial borders for decades and one by one they have mostly had be removed. Year on year shrubs grow and take over more space in a border. Some can be kept looking good by pruning, but many cannot. The shade they cast and the competition they introduce is detrimental to the perennials surrounding them resulting in either poor growth or lanky growth that calls for staking.
My ideas for the perennial meadow aim to create a bold and simple use for herbaceous perennials within the designed landscape. I hope to show landscape architects that these plants can be organised into effective design elements that can hold their own amidst blocks of shrubs, trees and buildings. If they are to succeed, they have to be both quick and easy to install and also easy to maintain year on year. This last point is especially pertinent as my experience with commercial clients is that while a budget may exist for the installation of a scheme, its subsequent maintenance will be minimal. The most you can hope for is a sporadic tidy-up and rarely will there be experienced staff time available for the sensative management of a complex mixture of shrubs and perennials. In our own gardens things are different and we can take the trouble to cosset our plants.
In designing a planting scheme for a garden I will not mix perennials with shrubs. Instead, I prefer to place the shrubs needed in separate beds where they have the room to grow and reach their full potential over time. By choosing perennials that need the same maintenance regime, which is often simply being cut back to the ground at the end of winter, the time and skill needed to keep everything looking good is minimised; shrubs would simple get in the way.
So where do I break the rules?
- There are some shrubs that take the same management regime as the perennials; perovskia, fuschia, vinca and ceratostigma can all be cut back low in the spring to return quickly and flower amidst a meadow of perennials. These small shrubs regularly play along as theme plants in my schemes.
- Specimen shrubs and trees need something around their base to create an attractive settting; circles of gravel or mulch look ugly, but a ground-covering layer of low-growing perennials can often complement them. However, such groundcovers take time and extra care to establish well and are more time consuming to manage than a simple open bed of perennials. My own back is a testimony to this!
- I have a small bed in front of a dark stained fence in my garden which features a scheme of dark leaved perennials – epimediums, astilbes, penstemons and primulas. It is a charming scheme with a succession of interesting flower colour and form. I decided it needed a bright background even though it is partly shaded and my solution was a couple of yellow leaved shrubs – Philadelphus coranarius ‘Aureus’. In the first year the shrubs were small and some of the perennials were too vigorous and needed cutting back to give them room to grow and establish. I know that in the future the table will turn and the shrubs will start pushing the perennials aside. The “meadow” is less than 2 meters/yards deep so it is no trouble to referee but no commercial client would bother.
So by all means mix shrubs into your perennial borders, but every time you do it your work load will probably increase.