With scant rainfall so far this winter, we are facing the real possibility of a third drought year in a row. Landscape irrigation in hot dry climates like ours accounts for more than 60% of the average household's water usage. Our primary efforts to conserve water must begin with seriously reducing the amount of water we use to irrigate our lawns and gardens.
Many gardeners, myself included, have never quite accepted that, here in the central San Joaquin Valley, we live in an arid, desert climate. We try to create lush green buffer zones around our homes that replicate the plantings in cooler climates. It's always a challenge, often a losing battle, to keep unsuitable plants and lawns alive during our long hot summers and we waste a lot of water doing so.
With the very likely prospect that, this summer, we won't have any water to waste, we need to change our mindsets, accept the reality of our very dry climate and re-evaluate the importance of each type of landscape planting-lawns, flowering annuals, hedges, vegetable gardens, shade trees, etc.
If we itemize landscape plantings by placing the thirstiest at the top of the list, we start by reconsidering the value of our lawns. Unless you're fielding a football team in your backyard, your lawn has only ornamental value. Lawn sprinklers can use up to 15 gallons of water per minute per sprinkler. Dead lawns may be ugly, but they can be replanted or rethought and redesigned with conservation in mind.
Mature perennial landscape plantings, including ornamental small trees, bushes and hedges may be able to survive the summer heat if heavily mulched and deep- irrigated once a week by drip emitters. Newly planted young trees and bushes need regular deep watering during their first two or three years. Newer trees and bushes, even drought-tolerant varieties, might not make it through a bone-dry summer. Again, many of these trees and bushes are nice-looking, but can be replaced. Their demise can be an opportunity for creating a more water-efficient landscape.
Do we allocate precious water for quick color from flowering annuals? Or do we use that water to keep a small vegetable patch going? Or plant a few vegetables in containers that require very little water and that can be moved into the shade on the hottest days? Edible plants are generally given more value than ornamentals (unless they provide nectar and pollen for pollinators).
Keeping shade trees alive, if this proves to be another drought year, must be our first priority. Well-placed shade trees can reduce energy consumption by at least 10% to 15% and the shade makes the summer heat more bearable. Large trees that do not receive supplemental irrigation have not had a good, deep drink of water for two years now. Deep-irrigate mature landscape trees as they come out of winter dormancy with a bubbler attachment on a hose that slowly trickles water to soak the soil to a depth of one foot. If trees show signs of drought stress (twig and branch dieback, leaf browning), let the lawn die and use that water to keep the trees alive.