Whatever the summer brings water shortage is a major consideration for many gardeners. Here in England it seems to have rained continuously for the past year, however we know that we will hit a dry period at some time. In any case extremes of weather seem to have become a feature of recent years and we need to plant accordingly. Personally I am very anti an irrigation system, unless it is absolutely necessary. I would always prefer to plant for the prevailing conditions, rather than trying to overcome them. So here are a few tips to help you get the best results in your garden this year, whatever the summer brings:
Soil preparation and mulching
Early spring is an ideal time to improve your soil and make it more water retentive. Adding organic matter in the form of well-rotted farmyard manure or good garden compost not only improves the texture of the soil but also increases its water holding capacity. Most importantly it encourages good root formation: the healthier and more extensive the root system of a plant, the greater its ability to absorb water from a larger area of soil.
When planting always break up the soil at the base of the planting hole using a garden fork. If the soil is heavy and compacted add horticultural grit and garden compost.
Mulching the soil surface with chipped bark or stone chippings helps to prevent water loss and reduces evaporation by keeping the soil cool. Mulching is most successful if done when the soil is moist early in the season. A thick layer of bark (8cm, 3 inches or more deep) applied in early spring will trap precious moisture in the soil and prevent those weed seeds from seeing the light of day.
Planting for dry conditions
There is no shortage of plants that will thrive in growing conditions with little available water. Silver foliage subjects such as Santolina chamaecyparissus, Helichrysum italicum, Convolvulus cneorum and of course lavenders are obvious choices. The ever popular Brachyglottis ‘Sunshine’ is widely planted for good reason; it is tolerant of the most hostile conditions, including salt laden winds. Left to grow naturally it will form an open shrub up to 1 metre, 3 feet or more. The silver grey foliage is more subtle than the bright, hard-yellow flowers produced in summer. Clip these off when the buds appear to maintain a compact plant and more subtle effect.
Aromatic plants usually contain oil natural oils in their foliage to prevent desiccation in hot dry conditions. Thyme, rosemary and sage and other culinary herbs are therefore ideally suited to sunny, dry situations. In fact these growing conditions produce the finest, most aromatic foliage for culinary purposes and the most flowers to attract bees and butterflies. The thymes are particularly useful plants and are ideal to soften the edges of paths, patios and steps. The varieties of Thymus serphyllum form ground hugging mats of tiny leaves. In early summer they are smothered in lilac, purple, deep red or white flowers. Thymus vulgaris cultivars are shrubbier, forming low bushes of fine stems and tiny aromatic leaves widely used for cooking. The lemon thyme Thymus citriodorus ‘Doone Valley’ is a small spreading plant with dark green and gold foliage with a delicious citrus fragrance.
The purple sage, Salvia officinalis ‘Purpurascens’ is an underrated plant with soft mauve-grey leaves that turn become more purple in summer and steely-grey in winter. It grows quickly to form a low mound with spike of sapphire blue flowers in summer. Clip these off as they fade and trim as necessary to maintain a compact shape. This is an ideal subject to hide the unsightly foliage of Allium christophii whose sparkling lilac firework flowers look wonderful with the sage.
Cistus, the sun roses are well adapted to drought with their leathery or sticky dark green foliage and a long succession of white or pink flowers in early summer.
Cistus ‘Sunset’ is a stunning plant growing to 60cm or so in height with a compact habit and soft, pale green foliage. The blooms are like purple-pink tissue paper, shimmering and delicate, 3 cm across with golden-yellow eyes. Cistus obtusifolius ‘Thrive’ is a compact variety forming a low mound of neat foliage studded with pure white, yellow centred flowers in June and spasmodically throughout the rest of summer.
If you want something even hardier with single flowers then choose a potentilla. These hardy shrubs grow well on dry soils once established. Potentialla fruticosa ‘Primrose Beauty’ is a nice subtle colour that mixes easily with so many other plants.
Buddlejas are extremely drought tolerant plants able to grow in the most inhospitable conditions. They are well known for their fragrant summer flowers that are attractive to butterflies but some varieties also have attractive foliage. Buddleja ‘Lochinch’ has silver grey foliage that looks good from the moment the new shoots start to grow in spring until leaf-fall in the autumn. The rich lilac scented flowers in late summer are an added bonus.
The deciduous Elaeagnus ‘Quicksilver’ is one of the most wonderful drought tolerant shrubs with narrow willow-like leaves of bright silver grey. It produces tiny sweet scented flowers in early summer. It is an excellent choice to bring light but dramatic height to the centre of a gravel garden. Grow it with the emerald-leaved, sapphire flowered Ceanothus ‘Skylark’; equally vigorous and fast growing.
The perennial wallflower Erysimum ‘Bowles Mauve is a short-lived shrub with narrow dark green leaves on upright stems and spikes of mauve-purple flowers from spring intermittently through to autumn. On heavy wet soil it is short lived but on a scree bed it lasts longer and grows and flowers more prolifically.
Many perennials also thrive in dry, well-drained conditions. The low mounds and soft foliage and delicate flowers of herbaceous geraniums combine well with the lime green frothy flowers of Alchemilla mollis, both are a wonderful contrast to the spiky foliage and flowers of eryngiums. Later in the season the tall stems and bright purple flowers of Verbena bonariensis attract bees and butterflies as do sedums such as Sedum ‘Herbstfreude’ whose flat pink flowerheads persist and become mahogany in early winter.
Gravel provides the perfect medium for self-seeding subjects to germinate next year’s plants. Grasses such as Festuca glauca and Stipa tenuissima seed themselves liberally. The gardener just has to carry out a little judicial thinning. Annuals like the Californian Poppy, Escholtzia, with shimmering blooms in shade of glowing orange, create a sensational summer display. Plant them with low silver foliage shrubs and early flowering Helianthemums to prolong the season of interest.
Hebes are often recommended as plants for dry conditions. In fact many, particularly the larger leaved cultivars suffer in drought and need some moisture in the soil throughout the year. Small, grey-leaved varieties such as Hebe pinguifolia ‘Pagei’ and Hebe ‘Red Edge’ cope most successfully in hot, dry weather.
Scree beds are an excellent way of creating a wonderful growing environment which helps plants to cope with the vagaries of the weather. Look out for my post on scree beds coming soon.....