Hardy Border Plants
one of the glories of British gardens in summer is the astonishing array of hardy border plants we can grow. Most of them are herbaceous, dying down each winter and springing up with renewed vigour the following season. It was once the practice to grow such plants together in a herbaceous border, but in today’s smaller plots a bare border in winter is something to avoid. This has led to the idea of mixed planting, intermingling shrubs and other plants, including bulbs, so that interest and colour is never lacking for long from any area. If you have sufficient space, a herbaceous border will provide its own particular summer charm and will offer colour continuously from April to October as the different plants come into bloom. If you have no room for such a border, you can include some or all of the plants mentioned in this article in your general scheme.
Flowering from March until May, the lungworts (Pulmonaria) are among the earliest of these plants; they carry spikes of blue or red blooms some 250 mm (10 in) high. P. officinalis, known to old gardeners as soldiers-and-sailors, Jerusalem cowslip, or spotted dog, has flowers that open blue and turn red, giving both colours together on each stalk. P. saccharata ‘Bowles Red’ is bright red from the time of opening. An added attraction of many of these plants is the white spots or markings on the leaves. Lungworts, planted in October to March, grow well in any good garden, but they welcome some shade.
April brings forth the bright single or double yellow flowers of the leopard’s bane (Doronicum). There are a number of cultivars of various heights, one of the best being D. orientate ‘Miss Mason’, a single which begins flowering at around 230 mm (9 in), increasing to some 450 mm (18 in) by about two months later. This plant is sturdy and easy to grow almost anywhere. Flowering at the same time, the navelwort (Omphalodes cappadocica) makes mats of bright-green leaves, above which are held 150 mm (6 in) long sprays of blue flowers rather like extra large forget-me-nots. I find it valuable because it flowers on long after one would expect it to have given up, and it often produces a few flowers in the autumn as well. Its preference is for semi-shade and a soil that does not dry out in summer.
The silvery artemisias are worth growing for their decorative silver-grey, aromatic foliage, which makes an impact for most of the year. One of the brightest is a form of the southernwood (Artemisia arbrotanum) called ‘Lambrook Silver’, which can make a substantial plant up to 1m (3-1/4ft) high and wide. Another silver-leaved plant, the lamb’s tongue (Stachys olympica, formerly S. lanata), is one for the front of a border, preferably where its lax stems of felted leaves can spill over on to a path or paving; it attains a height of 300-450mm (12-18 in). If you do not particularly want the flowers, there is a non-flowering form called ‘Silver Carpet’, which stays neater for a much longer time (the flowering form tends to look a bit tatty when its pinkish summer flower-spikes fade). All such silveryare decorative from the time their first growth appears in the early spring.
The plantain(Hosta) are also grown chiefly for their ornamental foliage, although in some species the spikes of lilac-pink or white flowers which appear later in the season are by no means to be despised. By mid-April most have broad, or very broad, pointed leaves in different shades of green or blue-grey that may be edged or marked with bright yellow or white; the leaf surfaces may be ribbed in such a way as to appear corrugated or waved. It is not unusual to find 18 or more different plantain lilies listed in one catalogue although, confusingly, many seem to be sold under more than one name by different firms. These handsome plants thrive in shade – even under trees – yet most also do well in sun provided the soil is reasonably moist at all times.
May and June are the months when many of the best-known border plants bloom. The dazzlingly flamboyant oriental poppies (Papaver orientate) are joined by the multi-coloured spikes of lupins (Lupinus), the dainty, nodding columbines (Aquilegia), and the exotic blooms of the large . The massive buds of the border peonies (Paeonia) that have shown promise for weeks now burst open, and the stately spires of foxgloves (Digitalis), , and the blue anchusa are at their best. They are joined by the pale-yellow evening primroses (Oenothera), the feathery red, pink, rose-purple, cream, or white plumes of the (plants that revel in a damp spot), and the scented blooms of the pinks (Dianthus), which are also valued for their spiky, silvery foliage. It is the time, too, when that great family of bellflowers, the , from the creeping 50 mm (2 in) high Campanula pulla to the 1m (3-1/4ft) C. perscifolia, clothe themselves in every shade from blue to purple, pink, or white, some species continuing to flower right through to September.
A splash of real gold is provided by coreopsis, best in the short modern cultivars, such as Coreopsis grandiflora ‘Goldfink’ (syn. ‘Gold-finch’). Although only 250 mm (10 in) high, it blooms for several months. Equally long-flowering, one of the yarrows,filipendulina ‘Coronation Gold’, reaches almost 1m (3-1/4ft), its flat heads of button flowers being clothed with ferny foliage; another, A.filipendulina ‘Gold Plate’, grows half as high again, with massive yellow heads some 150 mm (6 in) or even more in diameter.
The fleabanes (Erigeron) provide colours of pink to near red or lavender to violet in their yellow-centred flowers, which resemble Michaelmas daisies. The flowers start to open in June and, in the modern hybrid cultivars, continue for many weeks. Heights vary from 450 mm (18 in) to 600 mm (24 in), and all require staking. Some of the fleabanes with the brightest colours have names ending in ‘ity’, such as the light pink ‘Charity’ and violet-blue ‘Dignity’.
The true geraniums, or crane’s bills, are perfectly hardy (unlike the so-called bedding geraniums, which are actually members of the genus). All have attractive foliage and a number of them flower for a very long season, if not always flamboyantly. All are undemanding as regards soil; many obligingly flourish in shade. The tall ones tend to flop after flowering, but if they are then cut to the ground they will make a fresh crop of leaves and look respectable for the rest of the season. Among the longest in flower (from May to June) are the pale pink, 400 mm (16 in) tall Geranium endressii; the double lavender-blue, 250 mm (10 in) G. grandiflorum plenum; the rose-pink, 250 mm (10in) G. lancastriense ‘Splendens’; and the lavender-blue, 450mm (18in) G. wlassovianum.
Few plants have been more improved by plant breeders in recent years than the day lilies (Hemerocallis): hybrids can now be had that bear trumpet-shaped flowers in many colours from June to August. The plants are happy in a wide range of soils; their heights vary from 450 mm (18 in) to 1m (3-1/4ft), depending on the cultivar grown, but all are tough and sturdy enough to be self-supporting. Although all these hybrids are beautiful as individuals, not everyone necessarily shows up well from a distance. I particularly favour ‘Golden Chimes’; its bright-yellow flowers contrast with the brown buds, and make up for their smaller than average size by their number and a flowering season as long as any.
Not to be forgotten is the catmint, Nepeta x faassenii. A favourite front-of-the-border plant up to 450 mm (18 in) high, it bears narrow grey leaves and sprays of mauvish flowers that open from May to September.
In July the later-flowering border plants that will carry the main display well into August and often September commence to bloom. They include the tall, white-flowered
maximum. Unless you particularly want single flowers – which are perfect, huge, white daisies – the double ‘Esther Read’ at 750 mm (30 in) and the slightly taller ‘Wirral Supreme’ will make a fine show.
Cautleya robusta, a member of the ginger family, can bring an exotic touch to a border at this time. Its light-green leaves are large, rather like those of the tender cannas one sees in bedding displays in public parks, but the flowers are much smaller, yellow, and carried on stiff mahogany-coloured stems. Given rich soil and moisture it can reach a height of 1.2 m (4 ft), but 1m (3-1/4ft) is more usual. In order for it to look really luxuriant I find it best to plant it where it will receive some shade for part of the day.
Light soil is the preference of the purple cone flower (Echinacea purpurea), which carries large rose-pink to crimson-purple blooms from July until the autumn. Although it will attain a height of 1m (3-1/4 ft), it has stiff stems and can manage without support in many gardens.
The blazing star (Liatris) is an oddity among border plants in that its spikes of July flowers open from the top downwards, giving them a club-like shape. The 600 mm (2 ft) high ‘Kobold’ cultivar of L. callilepis is perhaps the best available, with its intense lilac-coloured flowers. Equally unusual are the bergamots or bee balms (Monarda), whose flowers are grouped into shaggy whorls at the shoot tips. Most commonly grown are the cultivars of M. didyma, such as ‘Cambridge Scarlet’, ‘Croftway Pink’, and the purple ‘Prairie Night’, which reach a height of 600-900mm (2-3 ft).
Few plants can be easier to grow than purple(Lithrum salicaria), a wild plant to be found in abundance beside streams in the west of England. Although it enjoys moist soil it seems to grow well enough almost anywhere given a little sun. The tall magenta flower spikes that delight the eye from July to September are usually 600-900 mm (2-3 ft) high. ‘Firecandle’ is a cultivar of an intense rosy-red colour, while ‘Rosy Gem’ is one you can easily grow from seed. If sown early in a frame, the plants will flower in their first summer. One great virtue of these plants is that despite their height they are completely self-supporting. They should be cut back in autumn.
Pride of the late-summer border are the phloxes, with their fragrant mop-heads in shades of purple to lavender, red to pink, salmon-orange, or white. Most of them grow 750-900 mm (2-1/2 – 3ft) tall, appreciate plenty of moisture and food, and flower well in sun or shade. An added advantage is that many of them are sturdy enough to be self-supporting unless they are growing in a very exposed position.
Knotweeds are members of the largegenus, many of which have red or pink flowers grouped close together in short spikes, or ‘pokers’. Some of them are too rampant for a garden, but among the safe ones is the low-growing P. affine, which carpets the ground and is easily chopped back if it over-runs its space. The height of the June flowers is 150-250 mm (6-10 in). The best cultivar is ‘Donald Lowndes’, whose deep-pink pokers change to deep red by the autumn. Much larger is P. amplexicaule, which can reach over 1m (3-1/4ft) in height and width in moist soils. It is very free flowering and carries masses of small, pokery flowers from July to October. The species flower colour is pink, but it is nearer red in the cultivar ‘Speciosum’, and crimson-scarlet in ‘Firetail’. Although not flamboyant these polygonums are valuable for their long and late-flowering season as well as for the unusual shape of the blooms.
Among the plants not often seen in private gardens (perhaps because it must be increased fromrather than by division), but which never fails to catch the eye of visitors in public ones, is Salvia nemorosa (syn. S. x superba) and its cultivars. It makes a mass of upright stems topped with spikes of brilliant purple flowers in July and August; and if these are promptly dead headed by cutting the stems through just below the bottom flowers, they will make a generous repeat performance in the autumn. Growing 1-1.2 m (3-4 ft) high, it seems to do well in most soils and even in semi-shade, although it does need careful staking. It has two shorter cultivars in the 450 mm (18 in) ‘East Friesland’ and the 750 mm (30 in) ‘Lubeca’, which are otherwise similar in appearance to the type species but are earlier to flower.
Anyone who has met only the old, tall, invasive golden rod (Solidago) should take a look at the newer garden hybrids, which are much better behaved and thoroughly garden worthy. ‘Golden Shower’, for instance, grows but 750 mm (30 in) high and bears arching sprays of yellow flowers, while ‘Golden Thumb’ at a mere 300 mm (12 in) makes a hummock of short, yellow plumes.
Moving on to August we reach the time when the Japanese anemones begin flowering. Happy in sun or shade, and in almost any soil, they sulk when moved and should be left undisturbed as long as possible. They include Anemone japonica (more correctly, A. x hybrida) and one of its parents, A. hupehensis. The different cultivars offer single or semi-double flowers in white and shades of pink. The most beautiful, to me, are the whites, which show up well against a dark background. All flower on into October; the height range is about 0.6-1.2m (2-4ft).
Few people would recogniseclethroides as a plant related to the creeping jenny or moneywort ( ). Although it thrives in moist soil it seems to do very well under ordinary garden conditions, rising to a height of some 900 m (3-1/4ft). In July to September its stems are topped with white flower spikes. As these spikes develop, instead of standing up straight, as they do on most other plants, they arch over, all in the same direction, making an unusual sight. The leaves turn an attractive orange or red in the autumn.
Among the most showy plants for late summer are the heleniums (H. autumnale) with flowers, in colours of bronze-red to orange and yellow, made up of wide petals around a large central knob or disc. They grow well in most soils and even the taller ones are reasonably self-supporting unless caught in a heavy storm when in full bloom. Most of them grow to around 900 mm (3-1/4ft) high, although there are one or two, like the 600 mm (2 ft) orange-yellow ‘Wyndley’, that are shorter.
Stonecrops () come in a great variety of shapes and sizes, but none is more attractive than S. spectabile, also known as the ice plant. The light-green fleshy leaves, on thick stems that grow about 450 mm (18 in) high, are attractive all summer. They are topped by large flat heads of flowers in pink or rosy red that deepen as they age from August to October and never fail to attract butterflies and bees whenever the sun shines. Taller by up to 300 mm (1ft) is a cultivar called S. x ‘Autumn Joy’. All the stonecrops are completely self-supporting and compact, and must rank among the top 10 border plants.
One of the latest groups of border plants to flower (in September and October) is the Michaelmas daisies (Aster), the most labour-saving being the dwarf varieties, such as mauve A. novi-belgii ‘Audrey’, purple-red A. n-b. ‘Dandy’, and white A. n-b. ‘Snow Sprite’, none of which is taller than 300 mm (1 ft). Other cultivars can be had in heights up to 1.2 m (4 ft) and in a very wide range of colours. These, too, are mostly derived from A. Novi-belgii. Although the last galaxy of coloured daisy flowers in the year, they have disadvantages in that they are nothing to look at during the summer and often suffer from mildew and wilt. Mildew can be controlled by spraying with a suitable fungicide, but wilt is incurable, and if it is exceptionally troublesome your only recourse is to grow the few available cultivars of the closely related A. novae-angliae that are guaranteed to be completely immune to it.
Most border plants need to be lifted and split up occasionally, when they have exhausted the soil or threaten to encroach on their neighbours’ territory. Use young pieces from the outer edges of the clumps for replanting. Some of these plants, however, especially the peonies and Japanese anemones, are best left alone as long as they continue to flower well. Simply scatter a little bone-meal around them and spread a 25 mm (1 in) layer of well-rotted farmyard manure, garden, or even peat over the soil to act as a mulch.
A great many border plants are easily propagated by cuttings made from the new shoots in spring. Gather the shoots when they are about 100 mm (4 in) long, making sure in the case of delphiniums, lupins, and other hollow-stemmed plants that you sever them low enough for the stem base to be solid. Carefully trim away any leaves from the lower half of each cutting, and treat the cut end with a hormone rooting preparation. Then insert the cuttings in pots filled with a rooting compost, using a broad-based dibber to ensure that each cutting can sit firmly on the base of its hole; then gently press the compost about it. After watering the pots, cover each one with a clear polythene bag, using bent wires to hold up the plastic away from the plants and closing the bag about the pot with an elastic band. This will trap moist air about the cuttings to help prevent shrivelling before the roots form. Keep the pots in a frame, or even on the windowsill of a cool room, until they ‘strike’ (make roots). Light speeds root development, but direct sunlight could scorch the cuttings in their plastic tents. Once roots have formed, transfer each cutting into its own small pot. Grow them on until they are large enough to be planted out, taking care to harden them off (acclimatise them to the new conditions) beforehand in a cold frame or cloches.
A few border plants, such as anchusas, Japanese anemones, perennial blanket flower (Gaillardia), and oriental poppy (Papaver orientate), can be raised from. These are pieces of stout root, 25-50 mm (1-2 in) long, taken in autumn or winter. They are easily obtained when plants are lifted; alternatively, just dig away the soil from one side of a plant and remove a root or two. When preparing each cutting, make a level cut across its top and a sloping one at the base, so you know which way up to plant it. Set each cutting in the compost so that its top is just covered with soil. Put the box in a cold frame and keep it damp until new growth has developed, when the young plants can be potted individually and grown on.
Border phloxes are best divided if they are healthy, but if suffering from an attack of stem eelworm they can be raised from pieces of their slender roots, some 75-100 mm (3-4 in) long and buried horizontally 25 mm (1 in) deep in a box of compost. Gently but thoroughly wash all soil from the roots beforehand in order to avoid carrying the pest over into the new medium, and be sure to use a sterilised compost and clean boxes. Whenthe new phloxes, set them in fresh garden soil or they will certainly be infested again very quickly.
If you grow plants that need supporting, position the stakes as early in the season as possible so that the plants can arrange themselves naturally and help disguise the supports. If the work is left too late, the plants tend to have a ‘bundled-up’ look. If twiggy sticks are obtainable the plants can be supported in the manner suggested for hardy, pushing the sticks in among the developing shoots while they are still quite small so they can grow naturally through the mesh of twigs. It is more usual, however, to surround each clump with a number of canes of suitable length and to tie string around them to contain the shoots as they grow. (You can also buy proprietary brands of metal supports; although expensive, they should give years of service.) Whatever method you use, the aim of supporting is to contain the plants gently but in such a way that they cannot blow over or be weighed to the ground when heavy with flowers and rain. Do not force them to remain rigidly upright like soldiers on parade or you will destroy their natural grace.