Good plant selection is all about finding the right plant for the right place. You might be able to slightly alter your dry soil composition by adding some more organic matter to improve water retention. You can also add some more grit to improve drainage, but the quantities you need are enormous. It is far more sensible to consider the existing conditions in your garden and do your best to work within its limits. Sometimes it is the restrictions we face that stimulate the most creative solutions.
Dry soil can be caused by many factors. Dry gardens are common on the lighter, more sandy soils, found in the Fens and Brecklands in East Anglia. The heavy clay soils found in the east of the country in Essex will bake hard in the summer. Also, the thin, stony soils found on the South Downs can mean tough growing conditions for many gardeners. Adding organic matter will improve water retention. However, sometimes it is best to work with nature, rather than trying to overcome the challenges it poses.
Below are a selection of 25 plants which, once established, should be tough enough to cope with even the toughest, driest spot in your garden, thriving in even the hottest summers.
1. Juniperus Scopulorum ‘Skyrocket’
Junipers are a common plant to see on the dry soil of the Mediterranean. The distinctly narrow, columnar outline of ‘skyrocket’ can used to great effect as a vertical accent; punctuating crisp, geometric hedging in Italianate-style gardens. Their blue-green evergreen foliage adds a hint of coolness even in the blazing hot sun.
2. Helianthemum ‘Wisley white’
Helianthemums are also sometimes known as rock roses. These low-growing shrubs from the Mediterranean region can often be found growing in stoney, dry soil. They positively appreciate growing in full sun and with sharp drainage and they will reward you by flowering during mid-summer with a profusion of large white, saucer-shaped flowers with a yellow centre across their silvery grey foliage.
3. Euphorbia characias subsp. Wulfenii
Many Euphorbia species love the sun, and some have even evolved to look like succulents and cacti. One of the most popular varieties you will find in many gardens is Euphorbia characias subsp. wulfenii. This tall, clump-forming perennial has long stems with slender green-grey leaves. It will flower in the early spring with unusual, bright, lime-green flowers. After flowering it needs deadheading, but take care as their milky sap can cause serious burns to the skin.
4. Convolvulus cneorum
Most people are probably more familiar with convolvulus as the twining climber that will quickly smother your shrubs, also known as bindweed. It does however have a much better behaved relative. Convolvulus cneorum is a low-growing, gray-leaved shrub that thrives in a hot, sunny and dry position. Throughout the summer it will be covered with a profusion of small, white, trumpet-shaped flowers, much like its better-know relative, but much more welcome in the garden.
5. Erigeron karvinskianus
Also sometimes known as Mexican fleabane, this low-growing member of the daisy family is super easy to grow in dry soil. The tiny seeds can be mixed with a little compost and water to make a mud paste that can be daubed into cracks in old brick walls, in between block paving, or in a rock garden. It forms a low, wide, mat of deep-green foliage, covered with cheerful flowers through most of the summer. Be careful it doesn’t get out of hand, as it’s so easy to grow it can easily become a bit invasive.
6. Pittosporum tobira
This medium-sized shrub with glossy leaves has become a more and more common sight in gardens in the south of England. This is because drier and milder winters have meant that they can grow more easily over winter in a sheltered spot. It is commonly seen as a hedging plant in the Mediterranean where it thrives in the heat. If you give it a warm sunny and well-drained spot it will reward you in June with is beautifully perfumed flowers which fill the air with its heady aroma.
7. Eryngium agavifolium
Eryngium are sometimes known as ‘sea-holly’ because of their spiky leaves and blue-green colouring. This variety is slightly different as, for most of the year, it has a low-growing rosette of fleshy, spiky foliage, making it look more like a cactus or succulent. In June they will start to bloom with spiky flowers that look a bit like a thistle. They seem to be a favourite with all out of pollinating insect, and will fade and dry over the summer to a deep brown, standing like a modern-art sculpture in the garden through the winter, and looking fabulous when rimed with an icing of frost.
8. Salvia nemorosa ‘Caradonna’
Salvias positively relish hot, dry conditions and there is a huge range to choose from. There are culinary varieties like sage (Salvia officinalis), bedding plants (Salvia splendens), tender shrubs (Salvia microphylla) or perennials like clary (Salvia sclarea.) They all like hot, sunny spots and well-drained soil to thrive. Salvia nemorosa ‘Caradonna’ is often a ubiquitous plant at the Chelsea Flower Show as it can be relied upon to flower from late spring through most of the summer. It has deep purple racemes of flowers, which combine well with many other plants. Even when it isn’t flowering, it still has stunning deep purple stems to give colour, texture and interest in the border.
9. Phlomis tuberosa ‘Amazone’
Phlomis are sometimes known by their common name of ‘Jerusalem sage.’ There are several species commonly grown in gardens. The most commonly seen are the shrubby, phlomis fructicosa, and the perennial, phlomis russeliana. Both have grey leaves and whorls of yellow flowers, presented on the stem as if they have been skewered like a shish kebab. ‘Amazone’ is slightly more delicate, with smaller, more slender flower spikes in a pale purple colour. They start to flower in July, but will dry out and look fabulous combined with late flowering perennials and ornamental grasses.
10. Euphorbia myrsinites
Euphorbia myrsinites is a much lower growing form than its relative, characias subsp. Wulfenii, but it does benefit from the same striking combination of fleshy grey-green foliage and bright, lime green flowers. It will tend to creep over the ground and has much fleshier stem and leaves with very regularly arranged leaves which make it look more exotic and succulent-like. It needs good drainage, but will thrive in any warm, sunny spot.
11. Nectaroscordum siculum
This member of the onion family is sometimes called ‘Sicilian honey garlic’. It pops up from a bulb in mid-spring and from a rosette of strappy leaves it will produce a single long slender stem topped with an umbel of bell shaped, nodding flowers with hints of cream, pink and green, all hidden under a dusky sheen. They are a very elegant plant in flower. The flowers are meant to have a honey-like scent which attracts bees, whilst the leaves smell like their close relatives, garlic. They even look attractive after flowering as the drooping flower heads become erect and spiky in late summer.
12. Sisyrinchium striatum
This perennial plant is a member of the iris family, and has similar clumps of sword shaped leaves, except each leaf bares a broad pale stripe down the each edge which makes their upright form all the more striking. In the summer they will produce a taller, spike decorated with clusters of star-shaped, pale-yellow blooms. They appreciate full sun and need to be grown in a well-drained spot. Too much moisture over winter will cause them to rot off.
13. Iris germanica
The bearded irises have to be one of the most dramatic plants in the garden. With such large, and attractive but short-lived flowers they really are the ‘Divas’ of the of the flower border, but a star many of us couldn’t bear to be without. They are originally from desert-like areas with only seasonal rainfall, so will appreciate a hot, dry and sunny spot. Make sure the fleshy rhizome is above ground level and is getting plenty of sun as this will encourage them to flower. It is worth considering that they won’t be in bloom for most of the year, but they do have very striking, grey-green, sword-like foliage which can contrast well with other textures in the border.
14. Hylotelephium ‘Matrona’
The sedums and stonecrops have been subjected to a few name changes over the past few years, which can prove confusing. But they are still very useful plants. The fleshy, dark-purple and grey leaves of ‘matrona’ make it a striking variety. It combines beautifully with grasses or finer leaved plants. In late summer they will bear pale pink flowers, which are loved by bees and the seed heads can be left in the garden throughout winter. This is definitely a plant with interest for all four seasons.
15. Cytisus x praecox
The broom family would naturally be found on poor, sandy, dry soils which have sharp drainage and very little nutrition. They are a member of the pea family so have nitrogen-fixing nodules on their roots. This enables them to grow in some of the most inhospitable locations. They love to be in a sunny location, and will be smothered with small, yellow highly scented flowers in spring which fill the garden with their heady fragrance.
16. Kniphofia ‘Tawny King’
Red-hot pokers are originally from South Africa, but have been a favourite in the garden for many years now. They store water in their fleshy roots and evergreen, strap-like leaves, so can withstand long periods of low rainfall, and positively thrive in the baking heat of summer. The tall, upright flower spikes of ‘Tawny king’ have hints of copper and bronze tones and look fantastic combined with reds and yellows in a typically ‘hot’ border.
17. Macleaya × kewensis ‘Flamingo’
Although it would be hard to tell from first looking at them, this statuesque perennial plant is a relative of the poppy and are often called ‘plume poppy’. They are tall plants and will reach over 6ft in the season, so need to be near the back of the border. The tall stems have deeply-lobed, steely-grey leaves. They are topped by plumes of tiny white flowers, opening from purple-tinted bud in late summer. Their fleshy roots act as water storage organs, so they can be grown even in very dry soil. However, they can add a touch of drama to almost any border.
18. Yucca filamentosa
The spiky leaves of Yucca are most easily recognise from the common house plants. However, there are a few varieties which have a frost-hardiness far in excess of their ‘tropical’ appearance. Yucca filamentosa leaves can be very spiky, so it’s best not to plant them too near a path or somewhere children might be playing. But they have a strikingly ‘architectural’ form which will convey the look of a desert better than many plants. In the summer, if they are happy, they will start to produce huge 2m flowers spikes covered with drooping creamy white flowers. The edges of the leaves are often decorated with curled threads. These can look incredible decorated with jewels of dew or frost in the autumn and winter.
19. Cerinthe major ‘Purpurascens’
This annual plant, with silvery, grey green leaves and drooping purple flowers is a favourite for cut flower growers to grow for foliage in their bouquets. However, it also looks great grown in among all the silvery foliage of the dry garden. It is easy to grow from seed, and can be sown direct. But is best started off under cover in early spring and planted out into its final position. In mild areas it can be a short lived perennial and may even self-seed in a hot sunny spot.
20. Dictamnus albus
Dictamnus albus is a great perennial that will thrive in hot, dry areas. The plants will grow to about 2ft tall with aromatic foliage and will be topped with spikes of pink, lily-like flowers. It is sometimes called the burning bush as, on warm days, the plant will produce an aromatic oil. This oil is extremely flammable and the plants can burst into flame if held near a naked light.
21. Eremurus ‘Cleopatra’
Eremurus are sometimes called foxtail lilies. They incredibly beautiful plants with tall slender stems up to 2m tall topped with a dense raceme of tiny, star-shaped flowers. They will add a vertical accent to the border and look great poking up through lower growing plants. Eremurus resent disturbance and competition from other plants. So they are best planted in larger gaps in between plants in the border and marked with a cane to avoid treading on them. They grow from a central crown with fleshy roots radiating out, so do look a bit like a starfish or octopus. These can be planted in a shallow, wide hole, but need good drainage in the winter, otherwise they can rot off.
22. Lavandula angustifolia ‘Hidcote’
Lavender is a highly popular plant and widely used because it is so easy to grow and has so much going for it. The purple flower heads arrive in early summer and are beloved by bumblebees. Lavender flowers have a relaxing scent and can be used in all manner of home made cosmetics, or even in small quantities in baking. The slender, silvery foliage provides a great contrast for other plants. They can be hard trimmed shortly after flowering to keep the plants short, bushy and compact.
23. Melianthus major
Melianthus is an evergreen shrub, grown for its impressive deeply-toothed, grey-green, pinnate leaves. It can be a bit on the tender side. However, if it is grown in a sunny spot and kept well sheltered from the coldest of weather, on a well-drained soil it can be left outside through the winter in Southern gardens. If it is happy, it will start to produce unusual Ruth brown flower spikes during mid-summer. But it is those fantastic leaves that most of us will want to grow it for.
24. Ferula communis
This giant variety of fennel produces masses of steely-grey, feathery foliage and tall stems topped with bright yellow umbilliferous flowers. It could easily be mistaken for fennel, which has many of the same qualities, but if you have the space to provide, go for ferrula instead for the extra impact from its lofty height. If it is happy it can reach 3 metres or more!
25. Erodium manescavii
This plant could easily be mistaken for a hardy geranium, as it has similar leaves flowers and seed pods. However, they tend to have a looser feel than traditional hardy geraniums. The thinner stems lend themselves to blending much more easily and sharing space more happily with other plants. The purple flowers are produced continuously throughout the summer. It will thrive in a hot, sunny spot with poor soil quite happily.
See all the sections in my Plant Guide here.