Weather in California has become less predictable, with significant shifts in temperature and rainfall patterns over recent years. According to the U.S. Drought Monitor, California is currently drought-free for the first time in 25 years. As of mid-January, the state’s major reservoirs are at 130% of capacity and the Sierra snowpack is at 89% of average. However, there are concerns that drought conditions could return if sufficient rainfall does not occur during March and April, which are typically key months for precipitation in the Central Valley.
The Central Valley’s summer growing season now starts earlier, in April, and can extend until mid-October. During this period, daytime temperatures frequently surpass 100 degrees for longer stretches, while nighttime temperatures remain above 70 degrees for weeks at a time. The winter dormancy period has also shortened, reducing the cold hours necessary for optimal fruit and nut production.
Gardeners are advised to pay closer attention to microclimates within their gardens as these changes intensify. “Determining the best and worst growing spots can help us make adjustments for existing plants and trees as well as help us choose new plants and trees that can withstand long hot summers, persistent drought conditions and atmospheric river bombs that leave behind soggy soil and thick fog on winter days,” wrote UC Master Gardener Elinor Teague.
Plant hybridizers and growers are working on developing plant varieties better able to tolerate weather extremes. Microclimates within gardens—created by factors such as sun/shade patterns, wind direction, structures that affect rain or wind flow, and different soil types—are becoming more important to consider when planning planting strategies.
“Most every growing thing needs afternoon shade during Central Valley summers,” Teague noted. She explained that it is not always possible to plant shade trees or large shrubs on every property’s western or southern sides. Some garden areas may be unsuitable for planting due to excessive heat or sunlight exposure.
For sunnier spots with little shade, irrigation should be tailored not just to drought-tolerant zones but also according to each plant species’ needs and how much daily sunlight each spot receives. South- or west-facing structures often reflect heat onto adjacent areas; structures blocking prevailing breezes can cause localized heat increases; large trees may create dry zones beneath them by absorbing significant amounts of water.
Improving soil quality is also recommended: “Amending the soil to improve water retention and drainage can no longer be a process of tilling in a single bag of compost or humus when planting. The benefits of adding copious amounts of organic materials to native soil will become obvious in just a few years as the soil itself begins to restructure significantly,” Teague said.
