Xeroscaping is the term for gardening while conserving water. “Xero” is the Greek word for dry, and the xeroscaping movement was, initially, especially popular in Denver, Colorado when the water department there teamed up with landscapers to develop plantings that needed only minimal water.
Groundcovers like 'Blue Rug' junipers and low growing sedums, as well as cranesbill geranium "Bevan" are useful. Also, grey-leaved plants like lamb's ears and dusty miller and lavender do not need a lot of water once established.
Shrubs such as Caryopteris and Vitex are also a good choice for saving water. Remember though, that when you plant a woody shrub, you need to water it well the first season to be sure that it gets well established and puts its roots down deep to sustain it during subsequent droughts.
The best annuals for dry gardens are lantana and geraniums, marigolds, and zinnias. Perennials with tap roots that push down deep into the soil for moisture, such as poppies, cone flowers, and Japanese anemones, are also drought tolerant. Other good choices are coreopsis (especially 'Zagreb'), butterfly weed, yarrow, portulaca, globe amaranth, Verbascum, and bee balm. Montauk daisies, yucca, and Russian sage are also light drinkers.
This is Moya Andrews, and today we focused on minimal watering.