Contemplating climate change and gardening

After several days of scorching temperatures and skies dusky with smoke from local wildfires, it seems an appropriate time to consider how climate change will affect the plant life that gardeners love so dearly.

As our California weather patterns become more unpredictable, it’s inevitable that changes will occur to our local ecosystems. Forests stressed by higher summertime temperatures, more frequent drought conditions, and bark beetle infestations will experience tree die-off at an accelerating rate. Wildfires will become more severe and frequent, burning natural habitat, gardens, and homes. Native plant communities will be forced to migrate to higher elevations as average temperatures rise — or die off if they can’t adapt.  The ability of plants to adapt to changes in precipitation patterns has wide-ranging implications for agriculture, forestry, grazing, the nursery industry, and home gardeners.

California’s water supply, already a critical issue in our naturally arid state, will become an even more pressing issue as our state’s population continues to increase. Mandatory water rationing and water metering for all homes will probably be the wave of the future.

Our family lives in a neighborhood without water meters. We’re extremely conscious about both our interior (home) and exterior (garden) water use, to the point of allowing our never-used front lawn to go mostly brown in summer while we plan a more water-wise landscape. (Sorry, neighbors!) It’s not very attractive at the moment; however, it’s far more discouraging to see other households be so wasteful with precious water. One neighbor runs front yard sprinklers every day on a too-long cycle, leading to wasteful runoff and persistent flooding of a drainage area that leads away from their property. Pay-for-usage water billing (rather than flat-rate charges) will hopefully encourage water conservation and reduce or prevent such misuse.

Weather patterns and water supply are inextricably connected to the health of our gardens and to the productivity of the farming operations that are such a vital part of our county’s economy. The potential effects of climate change are dire, but there is hope. We can all do our part to minimize human impact on our planet and to garden sensibly. Making appropriate adaptations now — such as implementing permanent water conservation measures and switching to water-sensible plants/crops — will help prevent potentially catastrophic consequences in the future.

Here are some ways to make water- and climate-sensible changes to your home landscape:

  • Convert gardens from high-water-use plants to California native plants and low-water-use plants. Consult the WUCOLS IV plant list (http://ucanr.edu/sites/WUCOLS/) to learn more; it classifies hundreds of plant species by their water needs, from very low to high. (WUCOLS = Water Use Classification of Landscape Species)
  • Water plants and lawns deeply and infrequently (rather than shallowly and often). This encourages their roots to penetrate far into the soil, which in turn makes them more resistant to hot, dry weather.
  • When landscaping, use the principle of “hydrozoning,” or grouping plants together by their water usage. That way, irrigation systems can be adjusted to provide only as much water as those plants need. (Intermixing plants with different water requirements results in overwatering some plants to provide enough water to the thirstiest ones.)
  • Use organic mulches in planting beds to conserve soil moisture and keep plant roots cooler.
  • Use your powers of observation to see what plants look best under stressful conditions. Those that thrive are far better choices that ones that don’t. (For example, after the last severe drought, our local neighborhoods were riddled with dead, dying, or badly suffering redwoods and birch trees. These two species are naturally adapted to moist environments and they require lots of water; therefore, they’re poor choices for the Central Valley.)
  • Check your irrigation system to make sure all sprinklers and emitters are working properly, and fix any leaks. Also, watch for runoff; it’s a sign that water is being applied faster than it can soak into the soil. Adjust your irrigation timer to reduce the length of the watering cycle, or water in a series of shorter cycles.
  • Plant area-appropriate, deciduous shade trees on the south and west sides of your home, if possible. They will help shield your house from the afternoon sun in the summer, keeping it cooler and minimizing air conditioner use. In the winter, the leafless trees will allow the sun to warm your house, reducing the need for heating.

Red buckwheat (Eriogonum grande var. rubescens), one of many durable and beautiful California native plants. It’s an excellent choice for a garden adapted to tough climate conditions. (Kathy Ikeda)

I’m using a portion of my yard as a test plot for low-water-use plants, and I’m being intentionally hard on them. Not counting the initial year of plant establishment, this area gets deep, supplemental watering only a few times each year; I rely mostly on natural rainfall. Despite little water and mostly full-sun conditions, these California native plants are thriving and attractive: California fuchsia, California coffeeberry, red buckwheat, foothill penstemon, sedum autumn joy, deer grass, and two varieties of yarrow. Some other non-native plants—bidens, hybrid soapwort, and cape balsam—are also great successes.

One innovative experiment regarding plants and climate change is now under way at U.C. Santa Cruz. The newly installed Future Garden is a joint science and art project to determine which native plants respond best to the conditions expected to occur with climate change. Read more about it at http://ias.ucsc.edu/content/2018/harrisons-future-garden-ucsc-arboretum.

In these times of change, let’s all take the time to be conscious of our gardening practices, and to improve them for the benefit of our community and our planet.

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/CONTACT_US/.

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