The need for drought-resistant plants

Water scarcity and drought-prone soils are perennial problems for landscape architects and climate change means that they are likely to become more common – perhaps even the norm. Even high quality soils can suffer extended bouts of dryness in particularly hot summers, or protracted periods without rain. Brown lawns and wilted plants are hardly the best advertisement, so it’s essential as a landscaper or specifier to have a mental catalogue of aesthetically pleasing drought-resistant plants to bring into play. In this blog we will introduce you to some of the best low-maintenance drought-resistant plants for various landscape functions.

Maintenance musts

Although ‘low maintenance’ is often one of the priorities in plant specification for landscapers, there is no escaping that an extended dry period will necessitate further input, whatever the plants. This can be a good thing for those landscaping companies who offer a maintenance service, and it’s important to ensure that clients understand the general benefits in addition to the particular advantages in dry spells.

For a start, watering is really the only way to maintain traditional grass lawns at their best. Regular watering is also important for all plants that have been transplanted to dry soils throughout their first season – even those which adapt well to drought.

Weeding, too, is important during dry seasons. Quite apart from the aesthetic impact, removing unwanted plants also removes competition for precious water.

Plant selection and planting

There are some simple but effective planting techniques to employ in dry conditions, that can significantly boost the chances of your plants surviving and thriving. This starts with the initial selection of your plants. Usually, it’s best to choose smaller, younger plants when planting in dry soils. This allows them adapt to the conditions and build up resilience, increasing the chances of successful establishment.

Then, timing matters. If you are able, try to plant in autumn when working with very dry soils. This allows the plants to establish themselves and grow before the driest season. The exception is Mediterranean plants, which prefer spring planting to avoid the possibility of root rot. However, the reality is that briefs and timescales may not allow for optimum specification or planting conditions – clients may require instant impact, and transplanting may have to take place in high summer. In these cases it’s even more important to take care during the planting process.

Firstly, ensure plants have been soaked thoroughly for at least a day before transplanting. Generous quantities of organic matter should be dug well into the soil where they are to be planted. Mushroom compost, composted bark and well-rotted manure or garden compost are all good options.

Once in place, both fertiliser and mulch should be applied, and the plants watered in well. Avoid overdoing the fertiliser, since excessive growth will cause further issues, making the plant susceptible to frost in winter, likely to flop in summer and have higher water requirements.

What types of plant are drought resistant?

To survive drought, plants need a two-pronged strategy – to reduce transpiration (loss of water through stomata, pore-like holes in their leaves) and to increase water intake or storage. These strategies lead to recognisable characteristics of drought-resistant plants.

Plants with silver or grey-green or silver leaves, for instance, are often drought resistant: their foliage reflects rather than absorbs the sun’s rays, thus preserving moisture. Judiciously deployed in a landscape, silvery plants add elegance, interest and contrast. Try pollinator-friendly perennials such as rose campion (Lychnis coronaria) for long-lasting magenta flowers in summer and shrubs such as Caryopteris clandonensis ‘Sterling Silver’, which boasts beautiful blue blooms. There are options for silver-grey  groundcover (Santolina chamaecyparissus or cotton lavender), hedges (Pittosporum tenuifolium ‘Silver Queen’) and gravel garden highlights (Eryngium giganteum ‘Silver Ghost’ is a sea holly with particularly striking silver flowers)

Other leaf variations that lend themselves to water retention include very narrow leaves (as sported by many evergreen species), fleshy leaves, and hairy, spiny or waxy leaves. Besides evergreen and coniferous species, desert succulents and alpines are some of the biggest drought-resistant groups. In addition to their adaptive foliage, desert succulents often have specialist and extensive root systems that search wide areas for water, and can themselves act as a reservoir.

What are the best drought resistant plants?

Here is a selection of some of the most useful drought resistant plants for landscapers.

Hedging plants

Abelia grandiflora makes for a really pretty hedge, with shiny ovate leaves and delicate pink flowers which last throughout the summer. Abelia prefers a sheltered position, so for exposed landscapes, try Griselinia littoralis. This hardy hedging plant will not only withstand dry soils but windy and coastal positions. Its bright and glossy foliage retains its vivid hue all year round.

For formal hedging, or for privacy, you can’t miss with Buxus sempervirens ‘Elegantissima’. Compact, hardy and evergreen, ‘Elegantissima’ grows best in semi-shaded areas, and offers dense foliage with attractive cream edging. A taller variegated option is Ligustrum Ovalfolium ‘Audeum’ (Golden privet), which grows up to 4m and whose leaves have broad yellow margins. It is also low-maintenance.

Shrubs

One of the best places to start is Phormiums. With a huge array of both upright and arching varieties in a range of sizes and dramatic, often variegated, colours, these low-maintenance plants offer architectural interest for all parts of a landscape and require minimal maintenance. Find some of the best varieties here.

Similar to phormiums are cordylines or cabbage palms. Cordyline australis ‘Torbay Dazzler’ has wonderfully variegated foliage, with heavy stripes of creamy-white. Other architectural shrubs to try in dry conditions include euphorbias.

For flowering shrubs, Salvia and oak-leafed hydrangeas (Hydrangea quercifolia) are an excellent choice. Another is Californian lilac (Ceanothus), which comes in varieties of pink, purple, blue and white. This is a fast-growing shrub, and boasts a profusion of blooms in clusters, making it ideal for landscapes that require short-term impact.

Blue Spire (Perovskia atriplicifolia) is a small sub-shrub with wonderful violet-blue blooms, which emerge in conical ‘spires’ in late summer and autumn. Its aromatic silvery leaves are attractive in their own right. Plant Blue Spire in full sun.

Grasses

Growing up to 2m, oat grass (Stipa gigantea) makes a dramatic statement in borders with its airy plumes. The Japanese sedges Carex oshimensis ‘Everest’ and Carex oshimensis ‘Evergold’ are lovely mid-level grasses, between 30cm and 45cm, ‘Everest’ with distinctive yellow striped leaves and ‘Evergold’ with striking white and green. Hardy and low maintenance, they make a great addition to beds and borders.

For dwarf varieties and groundcover, try ornamental Mondo grasses (Ophiopogon japonicus), which come in a variety of stunning colours, and Carex testacea ‘Prairie Fire’, whose coppery orange colour in autumn adds warmth to wintry landscapes.

The dwarf lilyturf Ophiopogon planiscapus ‘Nigrescens’ is another stunner, perfect for gravel gardens. Its purple-green leaves can turn jet black in the right conditions, making it a striking point of interest contrasted against small wandering perennials.

Pennisetum, Micanthus and blue grasses are other good options for drought-prone soils.

Climbers

Climbers and creepers are sometimes overlooked, but are important for landscapers for frontages and creating wonderful features of fences, walls and other hardscaping, such as for covered walkways and pergolas. Luckily there is a wide range of climbers which do well in dry soils. Some of the best include akebia, clematis, ivy, climbing hydrangea, climbing jasmine, kiwi vine, honeysuckle, virginia creeper, passion flower and wisteria.

Perennials

Even in drought-prone soils, most landscaping briefs call for more colour than grasses and hedging plants alone can supply. Perennials are the final flourish to many a well designed landscape, and there are plenty available that will thrive in dry conditions.

Verbena rigida and Verbena bonariensis grow up to 60cm, and are topped with attractive and fragrant clusters of tiny purple flowers that last well into autumn, and which are made even more lovely by the butterflies it attracts.

All Salvias are drought resistant, but pollinator favourite Hot Lips (Salvia jamensis) is particularly eye-catching, with drooping, fragrant pink and white flowers which last from July to October. It is also fairly low maintenance, only desiring to be sheltered from cold winds.

Rock rose (Cistus creticus) brings forth wonderful papery blooms in a purple-tinged pink in the summer months. The yellow stamens add another level of interest. Try the ‘Sunset’ variety, and be sure to plant in full sun. Achillea, on the other hand, copes with partial shade and makes an idea plant for a dry border, coming in a wide range of shades from bright terracotta, yellow or cerise to muted dusky pink or off-white.

For a spot of colour in otherwise more barren seasons, try Mediterranean spurge (Euphorbia characias) which flowers from February.

Succulents and alpines

Succulents and alpines share a need for well-drained soil. They work beautifully as groundcover, in gravel or tapestry gardens, and even as feature plants.

Sedum dasyphyllum is a succulent that makes great groundcover, and is hardy down to -12°C. Echeverias, on the other hand, are grown more for their attractive evergreen rosettes of foliage. Echeveria ’Blue Frills’ is a particularly pretty option. Sempervivums are another wonderful group of succulents to try.

Alpines offer beautiful, delicate blooms – some excellent options include sea pink (Armeria), Dianthus ‘Pop Star’, which creates a compact mound of pretty pink flowers in summer. For purple colour, Veronica prostrata, a speedwell variety, is a lovely choice, while Sedum spathulifolium ‘Purpureum’ provides evergreen, purple-tinged foliage, with a mass of golden blooms in the height of summer.

If you are working with acidic soil, Lithodora diffusa ‘Heavenly blue’ is a great option. A mat-forming evergreen with attractive starry foliage, it brings forth small flowers of vivid blue in spring and summer.

This blog only covers a small selection of the wonderful array of drought resistant plants available, but hopefully makes it clear that, whatever your brief, and however tricky the conditions, there are always plants that can rise to meet them. Should you wish to discuss a project with one of our expert specifiers, get in touch with our friendly team today.

Feature image: by Sherry Wright on Unsplash