Growing a water savvy garden

We may be experts in supplying a clean and safe supply of water, but this National Gardening Week we spoke to the experts on how to use water wisely and still have a blossoming garden.

Here we talk to Nicholas Dexter, an award winning landscape gardener inspired by nature, who designed a Drought Garden for the Chelsea Flower Show and has plenty of tips on how we can follow his lead.

Look out for plants with smaller leaves or silver foliage that reflect the sunlight and therefore reduce the amount of leaf transpiration. Succulent plants are also worth considering as they have evolved to cope with drought by storing water in their fleshy leaves.

The Anthropocene is the current informal label describing our geological age, and will be viewed as the period during which human activity has been the dominant influence on the environment. Pretty scary stuff as the future of the planet is now in a delicate “moment in time”. Rather dauntingly, we are beginning to witness the early effects of climate change and on a more micro-scale the impact of this on our gardens.

Seasonal weather has noticeably shifted over the past few years resulting in a new pattern of hot-dry spring and summers often followed by second wave of dry weather in autumn. In the last decade the UK has recorded eight new high temperature records. Extremely wet winters and strong winds are also seemingly common meteorological events. It’s all quite extreme especially comapared to the typical British grey drizzle that has allowed people to garden so effectively over the past 100 years!

As a landscape designer, I am very aware of these new circumstances and make allowances for prolonged periods of both wet and dry weather. From a cost perspective, it is worth incorporating these features into a new project whilst the diggers are on site! However, there are plenty of simple ideas that can be adopted for any budget or scale.

In 2013 we teamed up with South East Water, Southern and Thames Water to create ‘The Climate Calm Garden’ at the Chelsea Flower Show. The concept showcased, in a creative way, how a small sustainable space could incorporate some key ideas for gardening in dry conditions.

These methods were:

1. Drought tolerant plant selection
2. Creating shaded areas by planting trees
3. Capturing and recycling rainwater
4. Irrigation (such as drip feed pipes buried below ground)
5. Mulching

The inspiration behind the garden layout was the angular, geometric mud-cracks seen in dry river beds. This was expressed as a network of metal irrigation channels that ran through the planting beds and seating area to transport water to deeper parts of the garden. The rear wall was fitted with guttering which flowed into a water-butt and pool. At intervals water could be released via a metal sluice gate which was also really good fun and very popular with visitors.

As part of the BBC coverage I had the pleasure of meeting Beth Chatto (now sadly no longer with us) in her Colchester garden to discuss her approach. She created her garden in the early 1990’s and her book ‘The Dry Garden’ is a valuable point of reference for anyone gardening in areas with low rainfall. Her mantra “right plant, right place” is one of the most practical rules to achieve successful planting combinations. Looking to nature and selecting species that grow natively or exist in hotter Mediterranean climates is a great starting point to choose species that are thrive in tough environments.

Here are some of my top drought tolerant plants:

Shrubs

• Santolina chamaecyparissus
• Cistus corbariensis
• Phlomis fruticosa
• Hebe rakaiensis
• Perovskia atriplicifolia
• Ballota pseudodictamnus
• Rosmarinus officinalis
• Lavendula angustifolia
• Lonciera pileata
  

Perennials

• Hylotelephium telephium ‘Matrona’
• Nepeta racemosa ‘Walkers Low’
• Thymus vulgaris
• Verbena bonariensis
• Euphorbia palustris / E. wulfennii
• Salvia officinalis
• Erigeron karvinskianus

Grasses

• Festuca glauca
• Seslaria nitida
• Helictotrichon sempervirens
• Nassella tenuissima
• Stipa gigantea
• Calamagrostis acutiflora

Of course, there are many other species that will happy cope with dry conditions. Look out for plants with smaller leaves or silver foliage that reflect the sunlight and therefore reduce the amount of leaf transpiration. Succulent plants are also worth considering as they have evolved to cope with drought by storing water in their fleshy leaves. Be mindful to select hardy succulents that are frost resistant otherwise they’ll suffer in the winter months (Sedums rather than Agaves).

Although Beth Chatto’s garden has never been irrigated, a really resourceful solution is to capture rainwater, when plentiful, so it can be used during the hotter summer months. This approach is becoming increasingly common in towns and cities and commonly referred to as SUDS (Sustainable Urban Drainage Systems).

The basic principle of rainwater gardening is to “slow the flow” from storm-cloud to drain by intercepting and storing water at every opportunity en-route. Methods of doing this are:

1. Green / Sedum Roof:
   Any flat or gently sloping roof surface which is in good repair and structurally sound can be converted into a green roof. Green roofs can be either supplied as turf roll or as interlocking pre-planted modules. The benefits include increasing biodiversity by providing habitats for wildlife. They also reducing the amount of surface water runoff.
   
   
2. Water butts & Attenuation Tanks:
   Water that filters through a green roof will then flow into gutters, which are generally connected to waste-water gullies. Adding a water butt is an easy way to collect water. A much larger, below ground attenuation tanks can collect a much larger volume of rainwater which can be linked to a drip-pipe irrigation system to water the garden during prolonged dry spells.
   
   
3. Swales:
   Rainwater exiting the rain waste downpipes can be diverted into other areas of the garden via Swales. These vegetated depressions can be planted with species that are happy in both dry and damp conditions.
   
   
4. Rainwater Ponds:
   A larger garden can include a rainwater-pond which acts as a reservoir allowing water to be pumped elsewhere when needed.
   
   

Therefore simple changes can make a big difference. If planning a new garden then do factor in attenuation tanks, swales and ponds. An existing garden can be edited by adding some new resilient planting and covering exposed soil with a think layer of bark mulch or gravel to lock in moisture.

Everyone should add a water butt. If you don’t want a “utilitarian” design then there are some stylish alternatives on the market. Whilst purchasing this then perhaps add a bird box too!

Rather dauntingly, we are beginning to witness the early effects of climate change and on a more micro-scale the impact of this on our gardens.