Succession Planting for Year-round Pleasure

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Structural plants are essential in any kind of planting, large-scale or small. They provide the feel of continuity and the core to achieving a long-season effect.

Foliage is the dominant characteristic of plants that give body to a planting. That doesn't rule out flowers, but flowers are not the essence of the contribution that anchor plants make to successions. Non-flowering plants are important for many reasons. Foliage makes a border more digestible. If you focus on flowers only, the impact hits your eyes so that they hurt. Foliage calms and has a unifying effect. It also prolongs a border's season so that it may well be year-round.

Leaves have great advantages. They are many-faceted, even more so than flowers. The larger ones create a sculptural effect and are inclined to be bolder than most flowers and for a longer period. Leaves have a great range of shapes as well as colours and textures and, whatever their size, they can be bold. That applies to bamboos and grasses, ferns and many perennials. There are also tender bedding plants with long-season foliage — cannas, castor oil plants, Tetrapanax, Eupatorium capillifolium and others on which I write later.

Leaves may be light-reflecting and glossy and aware of the state of the sky at any one time and certainly of sunshine striking them. Glossy leaves will also bring light into shady places. No corner of your garden, even where the side of buildings hems you in, need be dark or dismal. By contrast, leaves may be felted and light-absorbing and of velvety texture. They invite you to grasp them between fingers and thumb. Or prickly; the very hostility with which they confront you has its ownappeal. The pads of certain cacti may be far from cuddly, but they are often arranged on different planes, playing tricks with light and shade and thereby enhancing a feeling of depth and a heightened awareness of the third dimension.

Because of their 'look-at-me' element, I generally, in my own garden setting, prefer large-leaved plants to small. Gardens are, after all, for display. If leaves are tiny, as with heathers, the plant must fall back on colour for the effect it achieves. On the other hand, many colourful-foliage heathers have been bred and can give you sustenance year-round, the colours themselves changing with the season. And the plants will tend to be tougher than those which are large-leaved.

With some of us, variegated-leaved plants have great appeal. Fine, but don't grow many of them all together. They need more restful, less busy surroundings to set them off.

For ease of explanation, I categorize the different plants that give us structure, starting with trees. These are manipulated or not, according to scale. The size of the trees you can include in your borders also depends on the scale. If they are naturally slow-growing — and slow growers generally develop the most character — they will take a long time to become trees and will require no pruning at all. Cornus alternifolia 'Argentea' is like that. It rises slowly in horizontal layers, sometimes taking two or three years to make up its mind to grow the next layer. In the summer it is light and airy, with white-variegated foliage. When that is shed, you can enjoy its horizontal branch structure and you will notice how raindrops remain suspended on it, each catching the light and glistening. Who has need of flowers when there is such a paragon as this?

The evergreen Daphniphyllum himalaense subsp. macropodum is another slow grower. It follows the general rule that evergreens are less hardy than deciduous trees and shrubs, so you give it a bit of shelter. The more you see of this tree, the more you realize there is to see. Superficially its elliptical leaves, borne in rotate clusters, look like a rhododendron's, but they are not a bit. The undersides are smooth and silvery, while the leaf stalks, in winter, change to bright pink. Its 'look-at-me' qualities ensure that nobody ever misses it, whether standing close or as far away as sight lines allow. Close, you will appreciate that it is hung, just behind the leaves, with clusters of small, black, grape-like berries. We rarely prune it, but if some of its branches do begin to look a bit stemmy, you can cut them back and it will willingly 'break' from old wood.

A good Japanese maple, did you want? Fergus and I would wholeheartedly recommend Acer palmatum 'Sango-kaku' (alias 'Senkaki'). A small tree, in time, with brilliant green foliage in spring, the leaves quite small. Then prolonged autumn colour, yellow gradually deepening to gold. Finally, after leaf-fall, young twigs that are a really lively pink. But the first time I tried it, in my mixed border, it simply turned up its toes. I think conditions must have been too rich. Eventually it settled down in a comparatively poor piece of ground, acid, of course (none of these maples will put up with lime), and it gives us prolonged pleasure for a large part of the year. Acer palmatum 'Shishigashira' is not everyone's idea of the way a Japanese maple should look but its strong personality struck me from the first time I clapped eyes on it. I wanted it and I have it, doing a wonderful anchoring job, in the middle of a fluctuating melee of mixed border contents. Its upright habit is chunky and dense without being coarse. Its smallish leaves settle down to an unusually deep green and give a feeling of richness in late summer and early autumn, when much else is looking tired. Eventually the colour changes to burnished bronze, before shedding; that is not till November. Its winter aspect is scarcely less arresting. Next year's leaf buds are red but the web of young shoots behind them is overlaid by a soft grey bloom. Behind this, the older stems are olive green. Overall there is a purposeful concentration that inspires confidence.

There are other trees, excellent for mixed-border inclusion, whose size does need controlling; that is, whose growth needs shortening. Dickson's golden elm, Ulmus glabra 'Dampieri Aurea', is one such. On its young shoots, the gold-green leaves are arranged closely in two ranks and they overlap like feathers on a bird's wing. We prune ours over every other year, both so as to encourage plenty of young growth and to contain its loftiness to no higher than our tallest member of staff can reach from a ladder leaning against the tree's framework (Health & Safety authorities, please don't read). The whole tree, from a distance, shines like a beacon. It could be the continuation of the biennial mullein, Verbascum olympicum, which has similar upwards-reaching aspirations from a lower level.

Many Salix, the willows, lend themselves admirably to cutting back, usually termed pollarding in their case. So, in front of the elm I have a group of three Salix alba var. sericea, which is a particularly pale, silvery variant of our native white willow, S. alba.

One of my Long Border's most striking ingredients is a tall holly, lightly clipped with secateurs to make a slender cone at one end and at the back of the border, which is one-sided with yew hedging for a background. This is Ilex × altaclerensis 'Golden King', almost prickle-free (which makes for painless hand-weeding around it) and variegated with a yellow margin to a green centre.

There are some trees whose character is entirely changed by manipulation, which entails pruning back hard into old wood. They too are grist to our mixed-border mill. The tree of heaven, Ailanthus altissima, is most familiar in London and similar rather smoke-laden industrial centres as a tolerator of those conditions. But if you grow it from seed and, when the seedling is well established, make a practice of cutting it back each winter, almost to the ground, it will make a splendid foliage plant. Restrict its growth to one shoot and it will put on 4.5m/15ft annually, its pinnate leaves each more than 1m/3ft long. Although entirely hardy, this will create a thoroughly exotic effect. Paulownia tomentosa and Catalpa bignonioides respond in the same way, the latter particularly effective in the golden-leaved C. b. 'Aurea', which is immensely expensive because it has to be grafted on to plain-leaved seedlings and only the Dutch are doing it.

Other trees that have to be grafted are many deciduous variegated kinds, like the white-variegated sweet chestnut, Castanea sativa 'Albomarginata', and the even more beautiful but rarer golden-variegated C. s. 'Variegata'.