These are plants which link pools, streams and other water features with the rest of the garden. They are moisture lovers which like to feel the influence of water without being in it all the time; so that the soil in which they grow must be always damp but never (except for occasional short periods) be waterlogged.
Since aerobic bacteria work where there are normal air conditions and because of the presence of oxygen in well-drained topsoil, bog plants can be given a richer diet than aquatics. For this reason plenty of humus should be dug into the soil initially or used as mulches in later years. Well-rotted garden, farmyard manure, peat or leafmould are all suitable — the aim being to produce a rich friable soil which allows for the easy penetration of plant .
Bog plants can be established in spring or autumn and for maximum effect should be grouped in blocks of the same sort of plant. Their numbers include trees and shrubs as well as ferns, grasses, bulbs and herbaceous plants.
HERBACEOUS BOG PLANTS
This is by far the most useful group and includes many which are frequently grown in other situations, such as the herbaceous border or wild garden. Being moisture lovers, however, they give a much better account of themselves when the soil is permanently damp.
The aconitums are good summer bloomers with mostly blue, but sometimes white, cream or bicoloured, helmet-shapedon strong leafy . The roots are but since few people are likely to dig and eat them their cultivation should not be ignored on this account. Among the best are Aconitum napellus, the common monkshood, violet blue, and such forms as Bressingham Spire, deep violet and up to 3 ft. and Newry Blue, 3-1- ft. The rich blue A. carmichaelii (A. fischeri) grows to 21 ft. and the autumn-flowering A. wilsonii (by some authorities considered a variety of the preceding) grows to 6 ft. with large violet-blue . A. vulparia (A. lycoctonum ) is a climber reaching to 6 or 7 ft. in moist soil. It has pale yellow flowers.
The actaeas grow well in damp ground and offer both flowers and berries as cultural inducements. Actaea alba, the white baneberry, has racemes of white flowers on 12 to 18-in, stems, also deeply cutand white fruits. The red bane-berry, A. rubra, is similar except for scarlet berries and the cohosh, A. spicata, has purplish-black fruits.
Ajugas are adaptable and make good ground-cover plants in most situations — sun or shade, dry or damp — but nowhere do they give a better account of themselves than in soil which is constantly moist. The rich blue, nettle-shaped flowers come in short spikes and theare smooth and entire. Ajuga reptans, the common bugle of British woodlands, has a number of forms with variegated foliage, such as variegata, grey green and cream; Rainbow, bronze, buff, red and green, and atropurpurea, dark purple. There is also a white-flowered form.
The lady’s mantle, Alchemilla mollis, makes a delightful edging subject for a bog garden, particularly if it is planted where the frothy greenish flowers can be reflected in the water. The silvery cape-shaped leaves are also attractive, but since the plant tends toitself about rather too exuberantly, it is wise to remove the old flower heads as these pass from bloom.
Severalfavour the rich moist soil of a bog garden, particularly lessen, a garden hybrid of great charm with rounded, shining leaves and cup-shaped, rosy-purple flowers about 2 in. across in early summer It grows 18 to 24 in. tall and can be propagated by taken in early spring.
Aruncus dioicus ( A. sylvester) is a noble plant for key situations, with massive plumes of hay-scented, creamy-white flowers on sturdy 5 to 6-ft. Stems in early summer. The large, deeply divided leaves accentuate their effect. Moist soil and light shade prolongs the flowering season.
Few bog plants are more rewarding than the astilbes, especially when they are associated with waterside irises, primulas and daylilies (hemerocallis). Both the pinnate leaves and plumes of variously coloured, feathery flowers are attractive and, given moist soil at all times, the plants persist for years.
For garden purposes any of the Astilbe arendsii forms are the most reliable. These grow between 2 and 3 ft. tall, with pink, red,, crimson and white flowers. Representative varieties are Deutschland, white; , pink; Cattleya, pink with a touch of mauve; Fanal, deep garnet red; Federsee, bright red, and Amethyst, lilac purple.
Among the species A. davidii is outstanding for a really damp spot. The stems grow up to 6 ft. with the top 2 ft. packed with crimson-magenta flower plumes. The long-stemmed leaves are deeply cut and coarsely toothed. A. chinensis is a dwarf for a front row. Usually less than 1 ft. in height, it has fern-like leaves and deep purple-pink flowers. Astilbes are at their best in mid-summer and can be increased by division of the roots in spring.
Astrantias raised in ordinary borders never attain the quality of bog-grown plants. They need abundant moisture during the summer-flowering season and most borders fail them in this respect. Of erect growth, with lobed leaves and aromatic roots, they have quaint flower heads like tiny Victorian posies, set off by chaff-like bracts. Propagation is by seed ordivision in spring or summer. Astrantia maxima is pink flowered and up to 2 ft. tall but A. carniolica rubra with dull red flowers is the deepest in colour. This likes a little shade and another, A. major with rose and green flowers, is the most vigorous and can attain a height of up to 3 ft.
Even lilies will grow in a bog garden; the best for this purpose is undoubtedly Lilium canadense which grows up to 5 ft. under ideal conditions, or 2 to 3 ft. when less well situated. Plant the bulbs in autumn 6 to 10 in. deep in moist peaty soil. They dislike lime so chalky ground is unsuitable. The pendant, yellow, bell-shaped flowers are spotted with maroon and purple, with up to twenty blooms on each. L. canadense can be raised from seed but normally takes three to four years to flower.
L. superbum, the swamp lily of the eastern states of America, is another for damp situations. In very wet soil plant each bulb on a mound so that its roots go down to the water and the bulbs remain free of standing water. The roots should be in semi-shade and the flower stems running up to the sun and light. L. pardalinum, the panther or leopard lily, takes its name from the crimson-brown spots which speckle the reddish-orange, turk’s cap flowers. These are 3 to 4 in. across, but variable both in size and colour. The stems can attain a height of 8 ft. and like all lilies they should be grouped for maximum effect. Treat as for
L. superbum and divide the clumps every three or four years.
Camassias also belong to the lily family and make useful subjects for damp meadows and similar situations. They flower in early summer, with loose spikes of light to deep blue, funnel-shaped flowers, but white and cream forms are not uncommon. Camassia leichtlinii is the best species, but very variable ;plena is a double sulphur-yellow variety.
The little milkmaids or ‘faint sweet cuckoo flowers’ of Tennyson ( Cardamine pratensis) can be allowed to seed and naturalize in damp meadows or the wilder parts of the bog garden. Growing 6 to 9 in. high, they have cress-like leaves (once used for salads) and spikes of simple, pale mauve flowers. Plena, a form with double flowers, is more showy but has to be propagated by division.
The snake’s heads are Chelone glabra, white flowered, and C. obliqua, reddish purple, and they flower in late summer with terminal heads of small foxglove-like blooms on 2-ft. Stems. These need deep moist soil at all times.
Cimicifugas bloom in late summer and. Are often seen in herbaceous borders. But they are even more effective in bog gardens, either in sun or partial shade, with their graceful, feathery plumes of fragrant flowers on 5 to 7-ft. Stems and smooth, doubly compound leaves. Cimicifuga racemosa is one of the best, especially in the varieties Elstead White and White Pearl but C. dahurica and C. cordifolia follow later in the season and are useful on that account.
Eupatoriums are coarse perennials with large, flat, terminal clusters of white or dull purple flowers and nettle-like or slender pointed leaves in whorls. They are useful for late summer colour especially in the rougher parts of the garden. Eupatorium cannabinum, the hemp agrimony, grows to 4 ft. and is dull purple which becomes more effective in its double form; E. purpureum, Joe Pye weed, is 3 to 4 ft. with 6 to 9-in., purplish-pink flower heads and E. rugosum (E. ageratoides), white flowered and 2 to 4 ft. tall, has nettle-like leaves.
Filipendula ulmaria is the meadow sweet, one of the most beautiful of British plants, frequently found alongside streams or in wet ditches. It is perennial with deeply cut leaves and spiraea-like plumes of small flowers. Under damp conditions it grows 2 to 3 ft. tall, or shorter where there is less moisture. The double form flore plena is the most effective or any of the foliage variants with golden leaves or cream and green variegations.
Banded in other shades. They are very striking with their unusual colouration and flat ribbon-like leaves. The species dislikes lime and needs to have the roots moist in summer but drier in winter. Named sorts (often with unpronounceable Japanese names) are available but mixedare usually very good and much more economical to buy. I. Kaempferi can be distinguished from I. laevigata by the leaves; there is a prominent midrib down the centre of those of I. kaempferi, but none on I. laevigata. The usual height is around 2 ft.
I. sibirica, also with grassy foliage, has several dainty flowers poised on each 2 to 4-ft. Stem. These make excellent cut blooms and are often grown in mixed or herbaceous borders. The flowers are mostly blue, but variable from pale sky blue to deep violet and mauve. There are also white varieties. Although the species and its forms will grow in dry borders and in sun or light shade, they give a better account of themselves in moist soil.
I. delavayi, a native of the Yunnan marshes of China, grows 3 to 4 ft. under favourable moist conditions. The flowers are deep violet with some white spotting and I. versicolor, with claret-purple flowers on 2-ft stems, is another for moist soil.
Hemerocallis (daylilies) are indispensable plants for the garden since they seem to thrive in almost any soil, climate or situation; indeed they have even been grown in shallow water. I have seen day-lilies in the arctic and others on the equator which gives some idea of their adaptability. Once established the clumps can be left undisturbed for years, the arching foliage attractive even when the flowers are not in character. The large, funnel-shaped, often fragrant blooms only live a day, but since modern hybrids produce countless buds the flowering season extends over several weeks. Besides such species as the tawny-orange Hemerocallis fulva and its double form Kwanso and H. citrina, pale lemon, there are countless varieties available, many of which are diploids. These come in a wide range of shades from palest lemon to canary yellow, tangerine, pinks (like Pink Domino and Pink Prelude) and crimsons (like Stafford and War Eagle).
Good late summer perennials are the lythrums and ligularias. The purple loose-strifes (Lythrum salicaria and varieties) have spikes of bright rosy-red or pink flowers on branching 2 to 3-ft. Stems. They should be massed for maximum effect and sited where the setting sun can shine on and through their petals, then they glow like fire. The best varieties are Brightness, rosy pink; Beacon, rosy red, and Robert, clear pink.
Ligularias belong to the daisy family and are linked — and frequently confused — with senecios. Nearly all the waterside types have large handsome leaves, tall branching stems and showy daisy flowers. They require plenty of water during the growing season and should be given plenty of sun.
Ligularia den tata (clivorum) has large kidney-shaped smooth leaves about 18 in. across and lots of rich orange flowers on sturdy stems which may go up to 5 ft. when established. It is inclined to be coarse, however, and should not be planted near weaker plants which it can smother, although it makes an excellent subject to grow near a stand pipe, as it masks the latter in summer. Varieties of the species are more popular for planting in water gardens, particularly Greynog Gold, which is more compact and around 3 ft. high with bronze-centred gold flowers; Othello, rich orange, and Desdemona, also orange but with purplish foliage.
L. hodgsonii has purplish overtones on the kidney-shaped serrated leaves and through these come clusters of rich orange flowers on 2-ft. Stems. L. japonica is the giant ragwort, a plant needing plenty of water when it will run up to 5 ft.; its orange-yellow flowers on branching stems.
The most arresting member of the group, however, is L. przewalskii (przewalskii), a very distinct plant with stately, wand-like, almost black stems. These grow 5 to 6 ft. high and are tightly packed along their upper lengths with bright yellow, raggle-taggle rosettes of flowers. The dark-stemmed, dark-veined, deeply jagged leaves are also handsome and as long as the roots are damp the plant thrives in sun or partial shade. All the ligularias can be divided in spring.
Lysimachia clethroides is a relative of the primrose and a Japanese species of 2 or 3 ft. with long, pendant,-like sprays of small white blossoms and broadly lanceolate leaves. It is suitable for sun or semi-shade. The great yellow loose-strife, L. vulgaris, is a British species, inclined to spread so best confined to wild garden settings. It has whorls of bright yellow flowers around the stems and tapering leaves. The Romans believed that the flowers put under the yokes of oxen kept them from quarrelling, hence the popular name.
L. punctata, also British and very similar but less rampant, grows around 1 to 2 ft. The golden-flowered, golden-leaved form of creeping jenny ( L. nummularia) is often useful at the edge of a pool since it makes a compact ground cover and will even grow down to the water. It is suitable for sun or partial shade.
hybrids are best treated as , the seed in spring under glass and then planting them out in moist soil and semi-shade. The large speckled and marbled flowers grow 6 to 9 in. in height and come in a wide range of colour combinations, but chiefly red, yellow and orange. Lobelia fulgens, the cardinal flower, with wine-red leaves and scarlet flowers is a dependable summer bloomer if the roots are moist. It grows 2 to 3 ft. tall and is best renewed frequently from cuttings and protected in winter.
Trollius and ranunculus are other moisture lovers, the former with round, globe-like flowers of yellow or orange. Trollius europaeus varieties grow 2 to 21- ft. tall and associate well with irises and primulas. Ranunculus acris fore pleno is a double yellow buttercup and R. aconitifolius fore pleno, the fair maids of France, has double white flowers. Both grow around ft.
Rodgersias have handsome leaves and sprays of spiraea-like flowers. Rodgersia aesculifolia has horse chestnut-like foliage and white flowers; R. pinnata, also with deeply divided leaves, is rosy red and R. tabularis (Astilboides tabularis) has yellowish-white blooms and round umbrella-like leaves.
Finally arum lilies ( Zantedeschia aethiopica) are often successful in bog gardens, particularly the form known as Crow-borough. The roots should receive plenty of water in summer but be kept on the dry side in winter; best effected by covering them with dry leaves and a polythene cover or laying pieces of glass propped on bricks over the crowns.