PHOENIX — With blazing summers and average annual rainfall totals of just 12.3 inches across the state, gardening in Arizona can be intimidating for those looking to start, especially if you live in the Valley.
ABC15 takes a look at the basics of gardening and what people can do if they want to exercise their green thumb year-round.
Climate Zones: What are they?
When you go to a store to purchase a plant or seeds, sometimes you’ll see a guide saying when it is best to plant based on your location’s “Hardiness Zone,” as set by the USDA.
The USDA Plant Hardiness Zones are determined by the extreme cold that a location may experience during the year.
Zones “do not reflect the coldest it has ever been or ever will be at a specific location, but simply the average lowest winter temperature for the location over a specified time. Low temperature during the winter is a crucial factor in the survival of plants at specific locations,” according to the USDA website.
Arizona hardiness zones range from 4b to 10b. Much of Maricopa County falls into the 9b zone, meaning that it does not get colder than 25° to 30° Fahrenheit.
A publication from the University of Arizona says that nurseries, landscapers, and gardeners in the Southwest commonly use the “Sunset climate zones” to choose plants.
The Sunset climate zones take overall temperature and conditions into consideration, not just the lowest lows.
Angelica Elliott, the assistant director of public horticulture at Desert Botanical Garden, says if a plant is not suited for your hardiness zone, there are things to do to help your plants thrive.
“A lot of times you can actually create your own what we call microclimates around your home,” Elliott said.
Elliott uses the example of yellow bells, or Tecoma, that can get damaged from frost, especially when they’re younger.
“A lot of times in order to prevent that sort of damage, that frost damage, you can plant it near a wall, a south-facing wall or west-facing wall,” Elliott said. “Maybe around a pool where it will get that reflected heat.”
For plants that grow in milder climates, Elliott says those plants might do well under a tree canopy that provides shade and cooler temperatures of four to seven degrees.
A publication from the University of Arizona breaks down the different climate zones and includes a list of trees and shrubs that thrive in their respective zones.
What can you grow in Arizona?
For those looking to get their gardens started, the middle of the summer may not be the best time to try.
Matthew Whitfill at Whitfill Nursery says it’s best to plant new plants in fall when it’s not as hot outside.
“Whenever the weather breaks,” he said. “It doesn't have to be nice outside, it just has to be not 110 outside. And that way everything gets fall, winter, spring under its belt before 110 comes along and beats it up again.”
Elliott says there are two growing seasons for vegetables in the Valley – the warm season (March through September) and the cool season (September through February).
Warm-season vegetables include asparagus, cucumber, eggplant, okra, peppers, tomatoes, pumpkins and zucchini.
“Okra does exceptionally well here in our Sonoran Desert,” Elliot said. “It could be a beautiful landscape plant because it has these beautiful yellow, almost like hibiscus flowers. And they’ll just bloom and produce fruit all summer long, and they’re really pest-free.”
Cool-season vegetables include artichoke, arugula, broccoli, carrots, cauliflower, garlic, various leafy greens, onion and Swiss chard.
For a longer list of vegetables and specific varieties, click here.
For those looking for landscape plants, both Elliott and Whitfill suggest looking around at what you see around you in the Valley.
"Like lantana, bougainvillea, Texas sage.. All the stuff that you see planted commercially, like in front of like commercial buildings work really well in a home yard, because it’s a lot less effort than, say, roses, or hibiscus or something that’s a lot more water hungry,” Whitfill said.
The University of Arizona has a guide on when to plant various fruits and vegetables, either by seeds, transplants, or sets of cloves, and when they should be ready to harvest.
Identifying and troubleshooting problems
Elliott says that when most people see a plant wilting, they think a plant is under-watered. However, wilting can be a symptom of both over and underwatering.
Before you give the plant more water, check the soil. If it is wet and the plant is wilted, then the plant is being overwatered. If the soil is dry and it hasn’t been watered for any amount of time, then the plant is underwatered.
Whitfill says another sign of underwatering is if the edges of leaves are brown and crunchy.
Elliott adds some plants, especially in the heat of the day, may wilt simply to cope with the heat. If that’s the case, the plant will perk up once it cools down.
“Sometimes you have to just kind of know your plant,” Elliott said.
If a plant is getting too much sun, it might become discolored.
Elliott suggests covering the plant with a shade cloth that blocks between 30% to 60% of the sun. If using a fabric that’s too dense, something that blocks more than 60% of the sun, it may block too much of the sun and keep the plant from photosynthesizing.
Whitfill says plants that are already established and have been around for a couple of seasons tend to be more resilient and may brave the heat better.
During cooler months, plants may suffer from frost damage. Leaves may become discolored and parts of the plant might die back.
“Believe it or not, here in the Sonoran Desert, we do get periodic episodes of cold temperatures,” Elliott said. “Although they don’t last like say, in the Midwest or back east, but we do get periodic periods of cold temperatures.”
When a freeze warning is issued, be sure to cover plants. The Desert Botanical Garden suggests using fabric such as burlap, old sheets or N-Sulate, a medium-weight UV-treated weight. The garden warns against using plastic, as that can cause plants to burn where it comes in contact with the plastic.
If you see pests on your plants, it may not require an arsenal of chemicals.
Elliott says another option is to manage pests with biological control. That means introducing another animal or insect to manage the pests.
“There’s certain animals that eat aphids, such as hummingbirds. So then you want to encourage the hummingbirds to come to your garden,” Elliott said. “Or if you have lace wings, or ladybugs, you know, you want to encourage them because they’ll eat those insects.”
Vegetable plants often attract more insects. One method is to use diatomaceous earth to manage them but be sure to purchase a food-grade product if using around vegetables or other edible plants.
Elliott says she’s even used a small, handheld vacuum to manage pests by simply vacuuming up the insects.
Seed libraries
Looking to start your garden but want to do it on a budget? Many local libraries have seed libraries, in which cardholders can “check out” a certain number of seeds at a time. For a list of libraries in Maricopa County with seed library programs, click here.
Classes around the Valley
Looking for more? Local community colleges, organizations, libraries and nurseries offer classes around the Valley. Some classes may require a fee.