Water is a precious resource locally and globally. Rainfall in Cambridge has averaged only 557 mm annually over the last 30 years and Cambridge’s climate is classified as ‘semi-arid’. The Dry Garden has been designed as a beautiful, water-wise planting suitable for a typical south-facing back garden in the City.
We have imposed a permanent hosepipe ban in the Dry Garden, but it nevertheless flourishes. This has been achieved principally through selecting plants that can survive short-term drought and using appropriate horticultural techniques, such as applying thick, moisture-conserving mulches and planting closely to help reduce loss of water from the soil.
Of the 100 different species that thrive here, many are Mediterranean natives such as Lavender, Thyme and Blue Spurge (Euphorbia myrsinites). Commonly, drought-tolerant plants have small leaves that reduce water-loss. They can be silvery and reflect heat, or hairy and trap moisture. Bulbs and annuals both demonstrate life-cycles that avoid summer drought and are featured strongly. Bulbs flower, die down and survive as underground storage organs through the summer, while annuals grow, flower and set seed early in the year to ensure the next generation in the space of just a few months. There are also a number of British endemics included, on the basis of many years observation of what grows easily in the Botanic Garden. These include Stinking Iris (Iris foetidissima), the Sea Buckthorn (Hippophaë rhamnoides), and even the Male Fern, Dryopteris filix-mas.
A pergola forms the backdrop to the Dry Garden and is draped with drought-tolerant climbers such as Clematis armandii and Vitis purpurea that provide light shade for the table and chairs here. This affords the perfect spot from which to take notes on how to incorporate water-wise gardening into your own garden at home.