Laying the Groundwork
Tips from the pros that can turn your garden into a climate-friendly setting.
By Nancy Erdmann | Photography by Nancy Erdmann and Art Holeman
This past summer was one of the harshest Phoenix and other low-desert areas have experienced in years, with the extreme heat racking up record-breaking temperatures and leaving rain gauges cracked and dry from lack of use. With the heat index finally dipping downwards, gardeners have begun the process of pulling out the plants that didn’t make it and visiting nurseries for suitable replacements that won’t succumb so easily to the desert’s natural extremes, but still provide long-lasting beauty.
With the cool-gardening season upon us, we reached out to the experts at Boyce Thompson Arboretum, Desert Botanical Garden, Tohono Chul and Tucson Botanical Gardens for their advice on how to refresh spent landscapes, as well as suggestions for what to plant.
Meet the Experts
Boyce Thompson Arboretum
Tammy Knight, Becky Stephenson and Gonzalo Ruiz, Horticultural Specialists
Desert Botanical Garden
Director of Horticulture
Tracey Till, Retail Greenhouse and Propagation Associate
Jo Falls, Director of Education and Guest Services
Tucson Botanical Gardens
Adam Farrell-Wortman, Horticultural Manager
Phoenix Home & Garden: How can gardeners get their landscapes back in shape for the fall/winter season?
Boyce Thompson Arboretum: Many woody plants that have died back completely or lost all leaves due to drought will grow back from the roots once adequate water resumes. If no bright-colored tissue is visible and/or the tissue is completely dry, it is safe to pronounce it dead, and it can be removed. When reintroducing water to drought-stressed plants, start slowly. Oddly enough, adding too much water right away will overwhelm the root system and can cause rotting and death. Only fertilize prior to periods of active growth, which in the desert are fall and spring. After a drought, be sure that root tissue has had time to grow back prior to feeding, as fertilizers can burn and kill plants.
Desert Botanical Garden: As the temperatures start cooling, it’s important to give your plants a recovery period. Prune the dead stems or leaves, but not too much, as you don’t want to add stress to the plant that is trying to recover. By spring, you will be able to tell how well your plants have been able to bounce back.
Tohono Chul: Cooler weather is beneficial for many organisms, including aphids. With the additional stress of heat and drought, aphids can potentially be more troublesome than usual. Spraying off your plants regularly with a hose or using a diluted soap solution will help remove them.
Tucson Botanical Gardens: Let this year be a lesson in the importance of proper mulching. Garden beds need 2 inches or more of mulch to maintain uniform moisture with less water use.
PHG: Many homeowners seek to emulate Arizona’s botanical gardens in their own landscapes. How can they create something similar in a residential setting?
Desert Botanical Garden: Native Sonoran and desert-adapted flora are always the first choice for creating a healthy, sustainable landscape in our climate. When starting with indigenous greenery, you eliminate high water usage rates and reduce the risk of introducing pest problems related to non-native plants. A desert plant palette is also adapted to the high temperatures, soil conditions and low precipitation we experience.
Tohono Chul: Decide on a cohesive theme for the entire garden or one for each large area, whether it’s a color palette or a regional style of landscape to help pull everything together. A sense of unity can be created using repeated elements, such as plants, paths, walls or colored gravel installed in a continuous way. Keep in mind that botanical gardens have staff, volunteers and invested resources all dedicated to creating beautiful scenery, so don’t be down on yourself if it doesn’t look exhibit-worthy right away.
Tucson Botanical Gardens: People should use native/near-native and arid-adapted vegetation placed closer together than the tags suggest. Fitting in a few more plants provides an extra touch of lushness when going for a botanical look. This works especially well with native varieties because they tend to be light feeders and drinkers.
PHG: What are some of your favorite desert or desert-adapted plants?
Boyce Thompson Arboretum: Daleas are tough desert legumes that self-fertilize, have low-water requirements, produce attractive flowers and can tolerate the cold. Penstemons are perennial native plants that feature a variety of striking blooms that attract pollinators and can handle our climate. And prickly pear cacti are a desert classic. They are relatively indestructible, thrive on neglect and come in an assortment of forms and colors.
Desert Botanical Garden: Desert milkweed (Asclepias subulata)—it’s all about providing for
the monarch butterflies; Queen Victoria agave (Agave victoriae-reginae) for its stunning compact rosette form and dark green leaves; beaked yucca (Yucca rostrata) with its almost prehistoric-looking form and tall stalks bearing bell-shaped white flowers; and of course, the saguaro, as it’s the movie star of the cactus world.
Tohono Chul: Santa Rita prickly pear is a tough cactus that is pastel green-blue in the warm season and purple in cool weather, and it produces bright yellow flowers in spring. I like Cleveland sage (Salvia clevelandii) for its therapeutic aroma, silvery-green foliage and tubular purple flowers. And ocotillo is an eye-catching accent plant, especially when in flower with its red birdlike blossoms. Few other plants look like it.
Tucson Botanical Gardens: I love any frost-hardy cacti, including hedgehog, pincushion, prickly pear and barrel. You can’t beat their ease of care or fantastic blooms. My favorite plant ever might be the creosote bush. It is an amazing example of life’s drive to survive (Carbon 14 dating of one specimen found it to be more than 11,000 years old) and its adaptability, being able to grow in the harshest of conditions. Native bunching grasses, such as the Muhlenbergias, are often overlooked in landscape design, but they should be considered staples. Not only are they attractive when given just a tiny bit of additional irrigation, they also add movement and rhythm in a landscape.
PHG: What blooming plants would you recommend for the cool season?
Boyce Thompson Arboretum: Some of our favorites are sweet peas for their fragrant, attractive flowers that come in a wide range of hues; calendula for its large, daisylike blooms that attract pollinators; sage, which produces very aromatic blue flowers; and ice plant, a succulent groundcover with vibrant pink, yellow or orange blooms.
Desert Botanical Garden: One of my all-time favorites is hop bush (Dodonaea viscosa), because it (depending on the variety) starts from a pale green and transitions into red; Texas olive tree (Cordia boissieri) for its height and form that provide screening almost year-round; Texas sage (Leucophyllum frutescens), a dependable, low-maintenance shrub that puts on a show with winter rains, seemingly bursting with color in a short amount of time; and slipper plant (Pedilanthus macrocarpus), a beautiful succulent that can develop red flowers that are quite stunning when planted in groupings.
Tohono Chul: Texas mountain laurel (Sophora secundiflora), an evergreen tree or shrub that provides an exuberant purple color in February and March and its flowers smell like grape bubblegum; Mexican honeysuckle (Justicia spicigera), which does great in partial shade and bears bright-orange tubular blossoms in late spring that make hummingbirds happy; and Baja fairy duster (Calliandra califorica) for its red stamen clusters that flower on and off year round and also draws hummingbirds.
PHG: What plants perform well in pots?
Boyce Thompson Arboretum: Mammillaria, Parodia and Gymnocalycium are all compact species of cacti that have colorful blooms in late spring/early summer. Also, small succulents, including petite species of aloe, Echeveria, Gasteria and Haworthia, are easy to care for and look lovely displayed together in containers.
Desert Botanical Garden: For color, I like using firesticks (Euphorbia tirucalli). They’re easy to maintain, and you can’t beat the orange-red color of their stems. I also like desert rose (Adenium) for creating a “wow” factor in the landscape.