Thinking about Shrubs – Part One – An Introduction

What, you might ask, is to be said about shrubs in a web blog devoted to the use of perennials in meadow gardens? Well, quite a lot really. I have visited enough so-called cutting edge, contemporary gardens with their wide drifts of perennials to know that without a good framework they can look and feel open and desolate. Trees and shrubs are some of the ways a garden space can be given structure and although in a small garden we may not need many, without them the experience is diminished.

10-0796I have been thinking a lot about the use of shrubs and trees in smaller gardens for quite some time now and the more I look and study the more I realise just how poorly they are understood and used. In a way perennials are easy. They grow into mature clumps quite quickly and we can consequently learn how to combine them into effective, long term schemes. In comparison, shrubs keep growing constantly changing the garden spaces they occupy unless of course we commit to pruning and sheering them.

I am still gathering my thoughts on the subject, but intend to use this blog to explore the subject of ornamental shrubs and garden trees in a series of posts in the coming weeks. One thing is clear to me; gardeners and designers need to start using these plants with more flair than is currently the case.

So lets make a start by listing the problems and shortcomings in the current use of shrubs in contemporary gardens:

Too much choice verses availability.

Visit any number of garden centres and I can guarantee that you will find the same assortment of shrubs on offer. This is understandable from a commercial point of view as the general public tend to buy what they know or what looks good growing in a pot. Variation within the assortment is immense and probably far greater than is the case when considering perennials.

For example, the choice of a phlox for a border scheme is between two species: earlier flowering Phlox maculata or the better known P. paniculata; thereafter it is simply a question of choosing a colour. Compare this with a shrub such as viburnum. Here we are faced with more than 150 species of which at least 20 offer highly valuable garden plants ranging from small, low-growing edging plants like Viburnum davidii through to tree-like V. sieboldii. One of the most elegant species, V. plicatum offers us plants with either rounded flower heads or flat sheets of fertile blooms surrounded by sterile flowers in the same fashion as lacecap hydrangeas. Amongst these forms there are many cultivars to choose ranging in size and habit – where do you begin?

Size can become a problem:

Knowing just how big shrubs will grow is never easy. Gardening catalogues tend to underestimate; perhaps not to scare customers away. Soil fertility and moisture can often make a big difference. But, plants seen in other gardens, especially botanic gardens and arboreta, are often very large due to their great age and the fact that they have never been pruned. The result is that people with small to average sized gardens are always looking for small compact cultivars and the nursery trade is eager to please, however, a large bold shrub may be just what the garden’s design needs.

Gaining experience of shrub growth rates, ultimate sizes and how to prune them is difficult to acquire, but essential for their effective use.

Books and magazine articles repeatedly emphasise the wrong characteristics:

Plant encyclopaedias are good for reference, but not for choosing the right plants for specific design objectives. However, all the books I have on designing with shrubs arrange the plants into groups such as leaf colour, flower colour and growing conditions, but size, form and leaf texture is really what matters. The colour of leaves or flowers is only secondary to building an effective garden landscape.Pittosporum tenuifolium 'Tom Thumb'

Evergreen Pittosporum tenuifolium ‘Tom Thumb’ forms naturally a low, rounded shrub. Its dark, shiny leaves are a feature all year and contrast well with the new season’s green shoots.

Placing and grouping shrubs in gardens has been following the same model for centuries.

Shrubs, like trees are traditionally used to create garden frameworks. Hedges and screens are obviously essential, but within the garden shrubs are still used to fill the background with maybe perennials in front as is to be seen in modern mixed flower borders. Perhaps it is time to find shrubs that can be moved forward in the scheme of things to stand out as sentinels to be circumnavigated; by pulling them away from boundary walls and fences the internal space of our smaller gardens can appear wider and deeper.

No repetition:

Apart from hedges and in rose gardens, the only shrubs we tend to use in multiples are evergreens such as buxus which we typically arrange into symmetrical patterns, for example, either side of an entrance. However, every planting designer knows that by repeating the same or similar plants throughout a scheme a sense of unity and rhythm can be introduced. Nowadays gardeners have started to learn to do this with perennials, but we still all tend to buy single shrubs and use them as specimens in our designs.

Pruning:

The more I study shrubs the more I realise how poorly I understand this important subject. The basic principles are simple, but the trick is knowing how to adapt these to get the most out of the shrubs we include in our gardens. The same plants can be used in quite different ways in our planting schemes once  a specific pruning strategy is selected.

Hydrangea paniculata

Hydrangea paniculata can be grown unpruned. It can be cut down in spring to control its height and depending upon how hard we chop it and the timing, we can choose just how high and when it will flower within our planting scheme.

So whilst shrubs bring their own challenges, once we understand them they can offer a huge range of possibilities to garden designers who are prepared to seek out exactly the right plants to realise their vision.

As always with a plant group, be taking a design lead approach to their selection and avoiding the obsessions of the collector, contemporary gardens offer exciting possibilities.

Syringa persica 'Lanceolata'Not all lilacs are tall, bold, but once-flowering shrubs with dull leaves. Search further and you may find Syringa protolaciniata (syn. S persica ‘Lanceolata’) which brings interesting textured foliage to a perennial planting scheme all summer long.

With the advent of the internet the most obscure species and cultivars are easily traced and acquired, no longer need we be restricted to the standard selection offered by the local chain garden centre.

Other posts in this series that might interest you:

Thinking About Shrubs in Gardens – Part Two – Top Criteria for Selecting Shrubs for Gardens

Thinking About Shrubs in Gardens – Part Three – Design

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