Waterwise Gardening: Living the Dry Life

One of the joys of a garden is that it is a living laboratory, full of opportunities for discovery. Most home gardeners have experimented with plants, learning through trial and error which ones will thrive in their local conditions.

Botanical gardens, including The Huntington, are no different. They just have the capacity to experiment on a larger scale and often over a longer time frame. When Henry E. Huntington hired William Hertrich, his first superintendent of grounds and buildings, in 1903, both were keen to cultivate and introduce as many nonnative ornamental and edible plants as would likely thrive in Southern California. Today, that horticultural legacy today benefits gardens large and small, public and private, and that continuing quest more of a focal point than ever due to climate change.

Many plants that were brought to California during the period when it was settled have become landscape staples. For example, of the myriad palms found at The Huntington and throughout Los Angeles, only the California fan palm (Washingtonia filifera) is native—and only to areas within the Colorado and Mojave deserts. It may be true that plants from almost anywhere will grow here; however, the key to growing them successfully, in many cases, has been to water them copiously enough to survive our long, dry summers. To highlight plants with more modest water needs, terms such as “California friendly,” “climate appropriate,” and “California native” have become common in nurseries, each with a slightly different focus on conservation.

One approach that waterwise gardeners can take is to plant only California natives. Yet California is a big state with habitats that range from alpine portions of the Klamath Mountains to the low desert of the Colorado and include coastal scrub, oak woodlands, chaparral, and riparian regions near waterways. Thanks to the profusion of microclimates that typify our state, native plants that thrive in Santa Monica might bake in Reseda, less than 20 miles away. Growing California natives successfully means taking some time to understand the features of your garden (location, sun exposure, drainage) and the plants you want to include in it.

Another option is choosing plants from regions with temperate, dry-summer climates similar to ours, such as southern Australia, central Chile, the Cape region of southern Africa, and the Mediterranean Basin. However, although plants from these areas may thrive in a place with similar temperatures and rainfall, they might also need a specific type of soil. Consider southern Africa and southwestern Australia, which were once part of the ancient landmass that geologists call Gondwana. These regions are dominated by infertile, acidic, and fast-draining soils. In contrast, geologically young California has fertile, alkaline, and often poorly draining soils. These disparate qualities can make it difficult to establish many southern African and western Australian plants in California, such as the flowering plants in the Protacea family.

“California friendly” species often include highly adaptable plants that thrive in regions with climates dissimilar to our own. For instance, the ubiquitous Bougainvillea is native to subtropical eastern Brazil. It is susceptible to frost but rugged enough to survive as a filler plant along the highways of Southern California. In like manner, the Silky Oak (Grevillea robusta), which originates in the lowland tropical rainforest of Queensland, Australia, has proven to be a tough, adaptable urban tree in the arid Southwest. These tall trees bloom in May, adding color along freeways with their vibrant gold-orange flowers.

Some plants are very drought tolerant once they are established, but it can be difficult for them to get established in the first place. For example, it is impossible to overwater newly planted Kangaroo Paws (Anigozanthos) because they need a lot of water to establish their root systems. And some plants that are not generally considered low-water users can withstand substantial dryness. Although Camellias are not at the top of any waterwise plant list, they are tough enough to survive in long-neglected Southern California landscapes. And even drought-tolerant plants are not necessarily drought tolerant when grown in containers, where they dry out more quickly than if they are planted in the ground.

For many people, “drought tolerant” is synonymous with cactus gardens, but clearly there is much more to waterwise plant selection than succulents. As Huntington and Hertrich understood, with gardening, fortune favors the bold. More than a century later, their experiments in acclimating new types of plants in our region are still yielding results. Botanical Gardens staff members continue adapting The Huntington landscape to a changing climate, inspiring others to do the same in their own gardens.

Kathy Musial, The Huntington’s curator of living collections, offers these pointers for establishing your waterwise landscape:

• Plant in the fall, while the soil is still warm. Roots will grow, even if the tops grow little or go dormant. New growth will appear in the spring. Although plant availability is often more limited in the fall, when you plant closer to summer, it is harder for the plants to establish themselves before the long dry season.
• The conventional wisdom is to till and amend garden soil. But apart from vegetable beds (which benefit from the addition of compost) and certain plants that need specific soil conditions (such as those in the Protacea family), it’s best not to till or amend the soil. Most plants will grow fine in our native soil. Especially avoid amending planting holes, as this will discourage the roots from growing out into the surrounding area.
• Plant from small pots; the smaller the pot, the stronger the plant will grow. Also, digging a hole for a 1-gallon pot is much easier than for a 5- or 15-gallon plant.
• Follow-up care is crucial, especially for trees. Water new plants by hand once or twice a week from the time you plant them through their first summer, after which they can be weaned off. Make a watering basin in the soil at the base of the plant to hold the water and let it soak in. Later, water a wider swath of soil around the plant to encourage root growth outside the original planting hole.

Sandy Masuo is the senior writer in the Office of Communications and Marketing at The Huntington.