Gardening in a changing climate
Case studies at RHS gardens
Wising up to water shortages at Hyde Hall
RHS Garden Hyde Hall spares the hosepipe by growing a sea of drought-tolerant plants.
RHS Garden Hyde Hall is situated in one of the driest areas of
the British Isles, with an average annual rainfall of just
600mm (24in); in 1996 only 451mm (17.7in) fell. This is a
lower annual rainfall than Beirut and Jerusalem. If the rain
didn’t fall so evenly throughout the year, Essex would
look like a desert.
Add to this heavy, unstable, Essex clay soil and the picture of a ‘challenging site’ is complete. All the work that has been done at Hyde Hall, and will be done in the future, is carried out with climate very much in mind.
The Dry Garden
Even during the devastating floods that submerged many parts of the UK in 2000, East Anglian gardeners knew that come summer, only a few days of hot, drying winds beneath clear blue skies would cause any amount of rain to evaporate, leaving plants wilting in the cracked and blanched soil.
The only way to garden successfully in these conditions is to understand the soil, the climate and the types of plant that will succeed. The Dry Garden has been designed and planted to demonstrate how plants of great diversity and interest can be grown without the need for artificial irrigation, thus preserving our precious water resources. The garden is supported by Essex & Suffolk Water, which is committed to encouraging the wise use of water through reduction of waste.
Drought-tolerant
plants prefer a free-draining soil and the heavy clay at Hyde
Hall needed improving with sandy grit. This helps with drainage
and improves the soil structure enabling plants to absorb
nutrients more readily. Drainage was further improved by creating
raised mounds made from rubble-filled subsoil and covered
with gritty top-soil. These could be replaced in the domestic
garden by mounding up soil in the borders or creating raised
beds.
The plants in the Dry Garden all originate from arid climates such as southern and central Europe, southern Africa, California, South America, Australasia and central Asia. There is a huge variety of plants that will grow in such conditions and for gardeners that have an area of ground baked by the sun through the summer, they provide year-round interest and none of the heartbreak of watching unsuitable plants burn and wilt.
To help identify subjects for a dry garden, look for the characteristics that plants have developed in adapting to these harsh conditions:
- Grey or silver leaves, which reflect sunlight
- Fine hairs or a waxy covering on the leaves to trap moisture in the air
- Swollen modified stems or leaves, such as succulents, that store moisture
- Small leaves and low growth habit to prevent loss of moisture through transpiration
Almost all further increase their chances in harsh environments by developing long, penetrating root systems which both anchor them in uncompromising terrain and seek out the last drops of moisture.
Dry Garden facts and figures
260 tonnes of gabbro, an igneous glacial rock from Scotland,
were transported from Huntley near Aberdeen for the large
boulders. The stone is usually crushed for road hardcore.
The largest boulder weighs over 8.5 tonnes.
800 tonnes of hardcore and sub-soil (to create the mounds).
460 cubic metres of soil and sandy grit.
70 tonnes of rounded flint (for mulch), laid at a depth of
40cm (16in).
80 tonnes of crushed concrete sub-base for the paths.
45 tonnes of Cedec (crushed red granite) for path surfaces.
Over 4,500 plants representing more than 740 different species
and cultivars.
It took three and a half months to build and three weeks to complete the planting. Some plants were placed and the surface mulch infilled around, others planted into the mulch. There is no geotextile layer under the mulch as its depth should be sufficient to suppress weed growth while allowing a degree of self-seeding from ornamental annuals and perennials.
Selected plant list with country of origin
| Ballota pseudodictamnus AGM Turkey | Beschornia yuccoides AGM Mexico |
| Ceratostigma plumbaginoides AGM China | Crepis incana AGM Greece |
| Diascia vigilis AGM South Africa | Echinops ritro AGM Central Asia |
| Eryngium giganteum AGM Iran | Euphorbia x martinii AGM South France |
| Gladiolus callianthus AGM East Africa | Jovellana violacea AGM Chile |
| Lavandula lanata AGM Mediterranean | Leptospermum rupestre AGM Australia |
| Lotus berthelotii AGM Canary Islands | Parahebe catarractae AGM New Zealand |
| Penstemon rupicola AGM USA | Rhodanthemum hosmariense AGM Morocco |
| Sempervivum ciliosum AGM East Europe | Senecio vivara AGM Argentina |
| Zauschneria californica ‘Dublin’ AGM California |