Adding light height to your planting

Plants that drift and add light and airy height amongst more solid subjects bring another dimension to a planting scheme.

Fine stems and small flowers have movement and a lively character that heavier shrubs and perennials lack. Planted in the foreground they change the perspective, further back in the border they help to link the layers of planting and soften the definition of their neighbours. Although some shrubs can fulfil this role, perennials and grasses excel, some of these really dance and sparkle in the border, especially later in the year; this makes them particularly valuable when it comes to maintaining the interest.

The delightful Gilenia trifoliata blooms in midsummer. Fine, branched red-brown stems carrying dark green leaves, each comprising three delicate leaflets, give rise to a cloud of tiny white butterflies. The effect is delicate and lacy and a lovely addition to lighten shrubs or bolder perennials. Although it will grow to almost a metre in height it fits in anywhere, even at the front of a border.

As summer progresses Gaura lindheimeri comes into its own. A clump of sage-green leaves, irregularly spotted with red brown gives rise to slender stems carrying delicate white flowers. There are pink forms, and in recent years more compact varieties. The latter lack the grace of tall cultivars such as ‘The Bride’ and ‘Whirling Butterflies’; these are the ones to grow, few plants have more movement or such a long flowering season.

The small flowered scabious and their relatives are wonderful as border plants and as cut flowers to add that airy quality to summer bunches. Knautia macedonica, with its delicate ruby blooms on slender stems blooms in midsummer. After the first flush of long lasting flowers it is best cut back to encourage a repeat performance. On well-drained soils it seeds freely and is a great drifter. The cultivar ‘Melton Pastels’ offers a range of softer colours but the species has a more lively quality.

The small flowered varieties of Scabiosa atropurpurea have been very popular in recent years. These can be raised from seed or plug plants and are good additions for summer colour in the border or for cutting. They like sunshine, good drainage and do best on alkaline soils. Attractive to bees and butterflies, they come in a range of colours including dark, almost black shades. These are “short-lived perennials”, so do not expect them to last.

Where space permits the giant of the family Cephalaria gigantea is worth growing towards the back of a border for light height against heavy shrubs. Its soft primrose-lime flowers look good against the dark green of yew or laurel.It can easily reach two metres or more and can become ungainly. Cut back after flowering to keep it in check.

Verbena bonariensis is probably the most popular subject used for adding light height to a border. Upright stems rise above other subject to carry clusters of tiny bright purple, orange-eyed flowers. Long lasting they attract bees and butterflies in search of nectar; left to seed finches hang on to the slender stems to extract nutritious seeds from the faded blooms. On light, well-drained soils Verbena bonariensis seeds freely and drifts in the planting. There are more compact varieties such as ‘Lollipop’, but most of the seedlings revert to the habit of the species.

Plants with fine, soft flower spikes add vertical interest, as well as that airy, ethereal quality.Perovskia atriplicifolia ‘Blue Spire’ is a shrub that loves a sunny, dry border. The fine branched stems carry tiny gentian-blue flowers from mid-summer. It is a great choice to plant alongside lavender to prolong the display and its slender habit is useful in narrow borders. Leave the white stems for winter interest and cut back in late winter to where new shoots are appearing low on the stems.

Linaria purpurea, purple toadflax is an attractive “weed” that can become invasive in gardens. Linaria purpurea ‘Canon Went’ is better behaved. Its spikes of grey-pink flowers appear at the top of straight stems clothed in grey-green leaves. Another lovely drifter it is useful amongst roses as it offers little root competition and does not challenge with its growth habits.

Veronicastrum virginicum, commonly known as blackroot is a much taller perennial. Blooming from midsummer its fine spikes of tiny flowers are much loved by pollinators. A prairie plant it associates well with tall grasses and the cultivars offer a selection of soft shades.

Many grasses reign supreme when it comes to adding light height to a planting scheme.Japanese art often features miscanthus in the foreground, the soft plumes magnifying the perspective and creating an illusion of space. The statuesque but delicate Stipa gigantea planted close to a terrace is an excellent choice for bringing that light height to the foreground. The soft tails of Pennisetum alopecuroides move gently in the breeze and add light texture, perfect with solid late bloomers such as Echinacea, rudbeckia and sedum.

We tend to think of diascias as plants for summer containers or sheltered situations in the garden.The ones most widely grown are rarely more than 30cm tall, but their greatest attribute is their ability to flower for months. Diascia personata, an altogether taller perennial also has this quality. It can flower from midsummer right through to autumn. The salmon pink blooms are carried high on finely branched stems. They quiver and move in the breeze and really shine amongst the soft blue of tall nepeta.