I was lucky enough to be in Denver last weekend - my first time in the state of Colorado. As ever when I travel, I seek out a garden or two to visit and a quick search on Google revealed the Denver Botanic Gardens to be only a mile or two from where we were staying downtown.
I was particularly interested to see the water-smart garden within the 23 acres of planting. Denver is known as the the 'Mile High City' and the air is pretty dry at that altitude. Added to that, the location of the state within the US – it's about as central as you can get, so moisture in the air will have been shed long before any weather front reaches here. As a result, this should be the perfect place to learn about gardening with limited water.
This particular area was situated in full midday sun and filled with plants typical of dry semi-arid regions with all the adaptations you might expect to ensure the plants' survival. The sloping border is watered only seven times during the summer season and plants are grouped together according to their water requirements. Thirstier plants are positioned at the bottom of the border to maximise their use of run-off or gravitational water.
Sedums were well represented - the photo below shows Sedum 'Purple Emperor'. Thick succulent leaves allow the plant to store excess water for use later.
Lavenders and Lamb's ears (Stachys byzantia) were also included in this garden. The former has reduced leaves and the latter has fine hairs covering the leaf surface. These characteristics serve to reduce water loss by transpiration. Both plants have a silvery colouring which acts as a reflector to the strong rays of the sun.
Agave, cacti, yucca, eucalyptus, oaks and cypress line the back wall of the border and create focal points in the central areas.
The photo below shows Texas sotol (Dasylirion texanum), a relative of yucca. Its distinctive flower spike appears from May onwards and grows to an impressive 15 feet in height - and is apparently adored by hummingbirds!
Many of the smaller plants featured along the front of the border such as salvias, alliums and fine grasses are those or close relatives of those that would be easily found in UK nurseries and garden centres. Maybe, if the drought conditions continue on our side of the Atlantic, we'll be taking the lead from here and planning our own future garden plantings in terms of low water requirements and heat tolerance.