A key characteristic of cacti, agaves, and yuccas is their tolerance of drought. Their adaptability to dry growing conditions makes them excellent choices for “xeriscaping,” a type of landscaping that uses xeric (drought-tolerant) plants. Since water is a limited resource in most of California and Nevada, it makes good economic and environmental sense for residents of these states to grow plants that can thrive on local rainfall. Our native cacti, agaves, and yuccas need the right conditions to thrive in a garden or container, but once they are established, many of them require little or no supplemental water.
Before growing these plants outdoors, it is important to find out how well a given species will do in a specific climate zone. For instance, Shaw agave (Agave shawii) will thrive from San Diego to San Francisco, but would probably not survive the high summer temperature and aridity of Las Vegas, a city better suited for growing desert agave (A. deserti var. deserti). Some plants, such as beehive cactus (Coryphantha vivipara), have a wide geographic scope and can tolerate a broad range of temperatures and soil types. Others, such as the limestone-dwelling Utah agave (A. utahensis var. utahensis), are more narrowly distributed and are more specific in their cultivation requirements.
Growing Plants in Containers
Growing small cacti, agaves, and yuccas in containers has many advantages. It offers more control over growing conditions and allows for specialized soil mixtures and watering regimes. Plants in pots are also transportable; they can be moved indoors to avoid frost damage or placed under protective shade to reduce excess summer heat. Agaves and yuccas are especially amenable to container cultivation because their roots tolerate crowding. Growing plants in containers, however, can be labor intensive. Potted plants need to be repotted every few years and require more attention to watering and fertilizing than plants grown in the ground. Plants in containers will dry out more quickly, and if placed outdoors, they will experience wider temperature swings than those planted in the ground or kept indoors.
In general, cacti, agaves, and yuccas cope better when under-potted, because an over-sized pot encourages over-watering, which can lead to rot. A deep pot that provides adequate room for roots is preferable to one that is too shallow. Soil mixtures in porous clay pots dry out more rapidly than those in plastic pots. Repotting with new mix rejuvenates the root system and assures that your plant is not rootbound. A paper towel or a piece of window screen placed in the bottom of the pot work well for retaining the mix while allowing water to pass through the pot’s drainage holes. Before re-potting, loosen the plant’s root ball and cut back any damaged or dead roots. Allow them to dry for a day or two; this will stimulate growth of fine feeder roots. Agaves and yuccas should be potted a bit high to avoid crown rot. Place them so that their lowest leaves are above the edge of the pot and where their crowns are unlikely to subside below the soil level. A top-dressing of clean gravel or colorful rocks aids in reducing moisture, helps keep soil in the pot when you water, and adds a finishing touch.
Most cacti, agaves, and yuccas need excellent drainage, whether they are potted and grown on a windowsill, or planted outside in a garden. Roots require air as well as water, and a soil that holds water to the exclusion of air will suffocate the roots. The easiest and often best choice for potted plants is a general commercial cactus and succulent mix with adequate organic material, perlite, and vermiculite; this combination will help to trap air, hold water, and prevent soil compaction. Many cactus and succulent growers make their own soilless mix with one part porous materials, such as perlite, vermiculite, or pumice, and one part organic materials, such as pine or fir bark, coconut fiber (coir), or composted peanut shells. Another recipe recommends one part commercial potting mix, one part pumice, and one part decomposed granite.
The right amount of water is critical to the survival of potted cacti, agaves, and yuccas. Provide water only when necessary. This may seem obvious, but giving too much water too frequently is easy to do and will surely lead to the premature death of your native succulent. Watering should be thorough, but allow the soil to dry out before the next watering. Our region’s native plants are most active from the late winter to mid-summer months; they require more water during this growing and flowering season than when resting or dormant. Their roots will still grow during the fall and winter, as long as some water is provided. However, avoid watering unless the soil is completely dry in the root zone. Since the watering regime depends on how often a plant dries out, relevant factors such as light, temperature, soil mix, and container size and type will also help dictate watering needs. In general, providing water every five to ten days during active growth, and every four to six weeks during dormancy, should be adequate in most situations.
Your plants will benefit from a light monthly fertilizing beginning in the early spring and through the summer. Dilute liquid fertilizers to approximately one-quarter of the label’s recommended strength. A fertilizer with more phosphorus than the other minerals, such as an N-P-K content of 5-10-5 or 5-10-6, is best for these plants. Our native cacti, agaves, and yuccas do not need any fertilizer during their winter resting season.
Most container-grown cacti, agaves, and yuccas will flourish in a location where you can maximize their sun exposure without scorching them. In the hotter climates zones, they generally do best with some partial shade that protects them from excessive summer heat. Newly potted plants should be gradually acclimated if they are being moved into a spot that receives full sun.
Growing Plants in the Garden
It is essential that garden-grown cacti, agaves, and yuccas have good drainage, so their roots do not remain wet and become prone to rot during cold, damp weather. If your garden soil has too much clay to provide adequate drainage, you will need to create a raised bed or mound using a commercial succulent mix. Adding large-grain sand, pumice, or clean gravel to your existing soil may be feasible for small areas, such as raised beds or mounds, and will help with aeration and drainage. Native succulents in the garden, like their counterparts in containers, should be watered more during the spring and summer. However, when compared to container-grown specimens, plants in the garden require less watering throughout the year and will dry out more slowly after each irrigation. Garden plants will also better withstand cold weather if the soil is not too damp. When planting agaves or stemless yuccas outside, follow the same advice used to avoid crown rot in containers; set the crown of the plant high enough so that it will not sink below what will be the eventual soil line when the soil inevitably settles. A mulch of rocks or gravel around your cactus, agave, or yucca serves several functions. It will keep soil temperatures near the root zone from getting too hot in the summer, offer some winter insulation, help retain moisture, and minimize weeds.
Native Choices for Cultivation
Many of our regional cacti, agaves, and yuccas have proven themselves worthy of cultivation in a container or in a garden landscape and are sure to add drama and diversity to any plant collection. Their placement in a garden landscape requires planning because of the hazards posed by spines, glochids, or spine-tipped leaves. A well-designed garden should account for proper placement of these plants away from traffic areas so that unwary visitors, children, or pets will not accidentally be stuck, poked, or gouged. These plants can also be difficult to weed around, so rid the area of weeds before planting. A rock mulch around the new transplants will also minimize weeds and insulate the root zone.
In addition to the ten species listed at left there are others that do well in cultivation and are available at some nurseries. For coastal regions of southern and central California, these include coastal prickly-pear (Opuntia littoralis), coastal cholla (O. prolifera), and coast barrel cactus (Ferocactus viridescens). Desert agave, Joshua tree (Yucca brevifolia), fishhook cacti (Mammillaria and Sclerocactus), and giant saguaro (Carnegiea gigantea) all do relatively well when cultivated outdoors in our desert areas, and any of these would make a spectacular addition to most home landscapes.
Excerpted and adapted, with permission, from Cacti, Agaves, and Yuccas of California and Nevada, by Stephen Ingram, published in 2008 by Cachuma Press (www.cachumapress.com).
The Top Ten Native Species
[with Sunset climate zones, where known]
Agave shawii (coastal)
Agave utahensis subsp. utahensis (interior)
Coryphantha vivipara (interior)
beehive cactus [1-24]
Cylindropuntia bigelovii (coastal)
teddy-bear cholla [10-24]
Echinocereus triglochidiatus (interior)
Mojave mound cactus [2, 3, 10-14, 18-23]
Ferocactus cylindraceus (interior)
desert barrel cactus [8-24]
Hesperoyucca whipplei (coastal)
chaparral yucca [2-24]
Opuntia basilaris var. basilaris (interior)
beavertail cactus [2, 3, 7-24]
Opuntia polyacantha var. erinacea (interior)
Yucca baccata var. baccata (interior)
banana yucca [1-3, 7, 9-14, 18-24]