Gardening and Drought

Prioritize Your Plants

• High priority plants are usually trees and shrubs that provide shade, are expensive to replace, and take a long time to mature.
• Medium priority plants are groundcovers, perennials (edibles, herbs, and flowers), and vines that grow quickly and are usually inexpensive to replace.
• Low priority plants are annual vegetables, herbs, ornamentals, and lawns – they are the least expensive to replace and reach maturity in a season.
  • The lowest priority should be given to lawns, which use a lot of water and are not sustainable in summer dry climates like ours.
• Remove medium and low priority plants from planting beds if they will compete with high priority plants for soil moisture.
• Use WUCOLS (Water Use Classification of Landscape Species) to determine the water needs of your plants. Consider letting go of high-water use plants (even those that are high priority).

Signs of Drought Stress

• Plants require the most irrigation in June and July when day length is longest. In August and September plant water needs begin to diminish as the days become shorter, despite temperatures that may remain largely the same. Dry winds also contribute significantly to drought stress and may occur at any time of the year.
• Primary signs of drought stress:
  • Wilting or drooping leaves that do not return to normal after the sun goes down
  • Upward curling or rolling of leaves
  • Yellowing and browning of leaves, especially along leaf margins and tips, or foliage that becomes grayish and loses its luster
  • Under-sized leaves and limited shoot growth
  • Interior needle browning and leaf drop on conifers and evergreens
• Secondary signs of drought stress:
  • Spider mite infestations
  • Increased damage by insects driven into home landscapes by lack of food and water
  • Increased feeding on landscape plants by wildlife
• Long-term consequences of drought:
  • Increased susceptibility to plant diseases and attack by insect borers
  • Root death
  • Diminished winter hardiness
  • Terminal die-back; dead twigs and branches
  • Eventual plant death

Irrigation Systems and Management

• Use and maintain drip irrigation to conserve water in the landscape.
• Hydrozone -- group plants with the same water needs onto the same valve or
• Move drip emitters away from the crowns, out to the dripline for trees and shrubs that have grown since the original irrigation was installed.
• The drip irrigation system should be set to run in cooler times of the day.
• Irrigate more frequently with shorter runtimes for sandy soil, so that water is not wasted below the rooting depth. Irrigate less frequently but with longer runtimes for loam, while clay soils benefit from a cycle and soak approach to reduce runoff.
• Over-irrigation is very common! Most established trees and shrubs can survive on 20 to 40 percent less irrigation than is normally Gradually reduce by no more than 10% at a time over several weeks to allow plants to adjust to less water.
  • Thereafter, a few deep irrigations spaced several weeks apart will keep most trees and shrubs alive through the summer. Many species will drop leaves/wilt when drought stressed but will survive.
• Get used to plants that don’t look perfect.
• Consider upgrading the irrigation controller to a ‘smart’ controller, which responds to historical and current weather conditions.
• Sonoma-Marin Saving Water Partnership Irrigation Scheduling Tool

Landscape Plants

• Hold off on planting anything new until the fall, to take advantage of cool temperatures and fall and winter rains (hopefully), since all new plants require a steady supply of moisture for 1-2 years.
• Water deeply every 3-4 weeks through fall and winter if there is no rain, to maintain plant reserves and the plants’ ability to handle drought stress during the summer.
• Keep beds weed-free, as weeds will out-compete plants for soil
• Add compost to planting beds – it acts like a sponge, holding moisture until plants need
• Apply mulch (2-3 inches) to prevent weed germination and evaporation from the soil Keep mulch at least 2” from the base of all plants and 6” from tree trunks.
• Avoid fertilizing and dormant pruning, since both will stimulate heavy top growth that will require additional water to support.
  • Spring and summer prune (April through July) plants that are too big or have excess This will lower water demand without stimulating a lot of new growth.
• If dieback occurs, prune out deadwood.

Native Plants

• Consider incorporating California native plants into your garden; native plants are adapted to our Mediterranean summer dry climate. Native plants  require water during dry winters.  Find more information on native plant care on our website : Tips and Tricks for California Native Plants. 

Edible Plants 

• If edibles are your top priority, see UC Master Gardener Program of Sonoma County publication ‘Food Gardening with Less Water’ on our Food Gardening with Less Water webpage.

Lawns

• Consider getting rid of some or all of your lawn by sheet-mulching those areas, converting the sprinklers to drip. Wait until fall to plant with low-water-use plants.
• Do-It-Yourself Lawn Removal Brochure

Other Water Conservation Strategies

• Find more information on how to conserve and protect water in the landscape on the following webpages on our website:
  • Conserve and Protect Water
  • Water Conservation recommendations
  • Water in the Landscape (see Water Conservation Recommendations section)

Additional Resources

• Extreme Weather and Gardening in the Age of Climate Change

March 2023