Raised beds or planters can be placed either in shady or sunny positions and plants chosen accordingly. For instance, if the bed is in shade you could have a delightful collection of peat-garden plants, grown in an acid, peaty compost.
Choose small-growing peat-garden plants, such as dwarf rhododendrons. There is a vast range of these but some of my favourites, which I can particularly recommend, are Rhododendron impeditum, a small mound of tiny leaves studded with purplish blue flowers; the prostrate R.forrestii repens with scarlet bell-shaped blooms; R. campylogynum with waxy bell-shaped flowers in pink or purplish shades; and R. keiskei with trusses of lemon-yellow funnel-shaped flowers in early spring.
Good companions for the rhododendrons are the cassiopes, small evergreen shrubs with white bell-like flowers in spring. Well-known species are C. lycopodioides and C. tetragona. A prostrate, spreading, evergreen shrub which can be allowed to spread over the edge of the planter is Arctostaphylos uva-ursi with white urn-shaped blooms in spring, followed by red berries. Small-growing gaultherias should be considered, like G. trichophylla, an evergreen with deep pink urn-shaped flowers in spring followed by attractive blue berries.
Lithospermum dijfusum is stunning in the intensity of its blue flowers. Try to obtain the variety ‘Heavenly Blue’. The flowering period is early summer to mid-autumn. Phyllodoce aleutica is a heath-like evergreen with globular, greeny yellow flowers in spring and early summer. Small-growing vacciniums are a good choice, too, like the prostrate, creeping, V. praestans with white or reddish bell-shaped flowers in early summer followed by red berries and brilliant autumn leaf colour.
There are two new dwarf pieris which would also be suitable: Pieris japonica ‘Little Heath’, a rounded evergreen shrub with small creamy white variegated leaves and pink-flushed new growth; and Pj. ‘Little Heath Green’ with glossy, bronze-tinted foliage. Surprisingly, these pieris do not produce flowers – they are essentially foliage shrubs.
If you want a more general planting scheme for a shady spot, then try the classical combination of hostas or plantain lilies, with their bold, ‘blue’, green, yellow or variegated foliage, candelabra primulas, meconop-sis or blue poppies, and ferns. These could be planted around a ‘framework’ of Japanese maples, varieties of Acer palmatum, noted for autumn leaf colour. Winter and spring interest could be provided by Lenten roses (Helleborus orientalis) and small bulbs like snowdrops (galanthus) and miniature daffodils (Narcissus cyclamineus and N. bulbocodium). Spring-flowering miniature cyclamen are recommended too.
In a position which receives plenty of sun why not consider a collection of alpines or rock plants? You could have a miniature rock garden – or perhaps a better description would be a scree bed.
A natural scree is a drift of broken rock at the bottom of a rock face – it does not contain much soil and is therefore very free draining. It makes a home, though, for many choice alpines. Similar conditions are easily created in a raised bed or planter. This feature looks particularly good in a modern setting. Do use a very well-drained compost: 10 parts stone chippings or pea shingle, 1 part loam, 1 part peat and 1 part coarse horticultural sand. Add a little organic slow-release fertilizer such as bonemeal.
A few well-shaped pieces of rock can be bedded into the compost before planting; and after planting the surface of the compost can be covered with a layer of stone chippings (if you cannot obtain these, use pea shingle which is readily available from builders’ merchants).
Although many rock plants or alpines will flourish in these conditions, I suggest trying some of the more choice plants, such as Androsace, Calceolaria, Daphne, Dianthus, Draba, Gentiana, Hebe, miniature Iris, Leon-topodium (edelweiss), Lewisia, Phyteuma, Saxifraga (of which there is a huge selection), Sedum, Teucrium and Veronica. Variation in height can be created with dwarf conifers, like junipers and pines.
Also for a modern setting, a bed of heathers and dwarf conifers can be recommended. This would be a truly labour-saving bed and by choosing a good selection of heathers you could have colour all the year round. You will need an acid or lime-free compost or soil, with plenty of peat added.
Dwarf conifers can include the deep gold Thuja occidentalis ‘Rheingold’; the greyish or bluish green Juniperus chinensis ‘Pyramidalis’; bright yellow Chamaecyparis pisifera ‘Filifera Aurea’; bright green Picea glauca ‘Albertiana Conica’; and silvery blue Chamaecyparis pisifera ‘Boulevard’.
Now to the choice of heathers for year-round colour. For winter and spring use any of the varieties (which most appeal to you) of Erica herhacea (also known as E. carnea), and Erica X darleyensis. For summer and autumn colour plant varieties of Calluna vulgaris (not forgetting some of the superb coloured-foliage varieties for additional winter interest); Erica cinerea; Erica tetralix; Daboecia cantabrica; and Erica vagans. Once the heathers have established and formed a dense carpet they will suppress annual weeds. The only attention they need (apart from watering in dry weather) is a light trim after flowering to remove dead flower heads. I would suggest mulching this bed with sphagnum peat to help prevent the surface of the soil from drying out.
