In the desert southwest, July means the arrival of monsoon storms which brings higher humidity and much-needed rain. Here’s what garden tasks you should do, which to skip, and things to watch out for during this changeable month.
July in the southwest garden is a month of changes. The monsoon officially starts June 15, but the first rains usually arrive in early July. Monsoon storms bring welcome rainfall, humidity, and cloud cover — all a great relief for your plants. And with the change in the weather brings some changes in gardening tasks.
July Weather Outlook
June is the hottest, driest month of the year. And while the average temperature doesn’t change much from June to July, the average humidity and rainfall go up considerably. This may feel less comfortable for you, but your plants will love it!
Here’s a look at June weather averages in both Tucson and Phoenix.
July Weather Averages (Tucson)
| High temperature | 100°F |
| Low temperature | 75°F |
| Precipitation | 2.45″ |
| Relative humidity | 40% |
| UV Index | 11.2 |
| Wind | 15 mph |
July Weather Averages (Phoenix)
| High temperature | 107°F |
| Low temperature | 84°F |
| Precipitation | .98″ |
| Relative humidity | 27% |
| UV Index | 10.3 |
| Wind | 8 mph |
If you live elsewhere, enter your city or town in the search bar at TimeandDate.com to find your weather averages. And you can find your average UV index at UVIndex.io.
What To Do in the Garden in July
July is a pretty quiet month in the garden since it’s not time to plant, prune, or fertilize. However, you need to continue to keep your plants hydrated, protect them from too much sun, and watch for pests. And be ready for storms and subsequent storm damage.
Here’s a snapshot of the activities you can do this month and those you should stop doing.
| ☑️ | Water deeply |
| ☑️ | Watch for heat stress |
| ☑️ | Watch for pests, weeds |
| ☑️ | Sow wildflower seeds |
| ☑️ | Be ready for storms |
| ✖️ | Don’t plant |
| ✖️ | Don’t prune |
| ✖️ | Don’t fertilize |
Read on for all the details and exceptions!
What You Can Plant in July
July is not a good time to plant desert landscape plants. Most plants will be much happier when planted in the fall, and there will be less work and worry for you, too.
But if you get the urge to plant, it’s not too late to sow summer wildflower seeds which germinate in response to the monsoon rains. Try to get them in the ground before the rains start.
These plants grow fast and will bloom this summer. Here are some places that sell and ship desert wildflower seeds, including “monsoon seed mixes” which contain favorites such as Arizona poppy, blanket flower, and desert zinnia.
Watering
You can continue to water on the same schedule that you used in June. However, once the rains come, you can skip the next scheduled watering any time you receive .5 inches of rain or more.
I use a rain gauge to keep track of my rainfall. If you don’t have one, you can check rainfall totals near you at the University of Arizona’s RainLog.org. This is especially helpful if you live around Tucson, and somewhat helpful if you live elsewhere in Arizona. If you live in Maricopa County, check out the county’s Rainfall Data page.
For more help on how to water your plants in July,
check out these articles:
How & Why to “Deep Water” Desert Plants
7 Tips for Watering Landscape Cactus
How to Water Desert Trees: How Often? How Much?
How to Water Desert Shrubs: How Often? How Much?
Now is a good time to think about harvesting rainwater. It doesn’t need to be anything fancy – simply collect it in whatever you have around that will hold water.
I have a rain barrel connected to a down spout, but I still set 5-gallon buckets around my roofline. (You can never have too much rain water!) Then I cover them with snap-on lids to keep out mosquitoes and critters that might fall in trying to get a drink.
With monsoon storms come power outages. If you experience a power outage, check your irrigation controller and reset if needed.
Most potted annuals need watering daily. If you’re watering with a hose, always check the water temperature first. Water from a hose can be hot enough to damage your plants.
Don’t Prune
While it’s OK to remove any damaged branches from trees and shrubs, July is not a good time to prune. Pruning further stresses your plants by exposing new areas to the sun and stimulating new growth.
Deadheading spent flowers, especially those in potted plants, encourages new flowers, and is “nice but not necessary” if you don’t feel like working in the heat.
Don’t Fertilize (with One Exception)
Most desert plants should not be fertilized in July. It further stresses plants by encouraging new growth which is easily burned by the intense summer sun.
The exception is potted plants. Potted plants benefit from a dilute solution of fertilizer every two weeks during the summer.
Watch for Iron Chlorosis
Iron deficiency sometimes shows up in the summer. The telltale sign of iron chlorosis is yellow leaves with distinctly green veins.
Desert soil contains iron, but it’s in a form that some plants can’t use, leading to deficiency. Iron chlorosis is especially common in non-native plants such as citrus, hibiscus, and gardenia. (Native plants have developed ways to absorb the iron they need from alkaline soils.)
If you have a plant showing signs of iron chlorosis, now is a good time to treat your plants. Learn how in our article Why Desert Plants Get Iron Chlorosis (& what to do).
July showers bring… weeds!
Pull weeds as soon as they appear.
New weeds are easy to pull when the ground is wet.
Watch for Garden Pests
The monsoon brings out more wildlife, some of which you may be delighted to see, and some, not so much. You’re likely to see more mammals, birds, snakes, toads, and insects.
Many desert dwellers find the monsoon season thrilling, but it’s not all good news for gardeners. Monsoon storms can bring flooding, hail, dust storms, and damaging wind. And an increase in moisture leads to an increase in insects, plant diseases, and weeds.
Watch for insect infestations on plants. Plants that have been stressed by heat and drought are more likely to harbor insect pests.
Some of the most common insect pests you may notice on your landscape plants this month include:
- ants
- aphids
- cochineal
- crickets
- hornworms
- leafroller moth caterpillars
- mosquitoes
- palo verde borers
- spider mites
Check around your yard for standing water which could harbor mosquitos. Empty pots, saucers, or any other forgotten nooks that hold water after rains. If you can’t empty them, add bits of mosquito dunks.
If you notice a cochineal scale infestation on your prickly pear cactus, hit it with a hard spray of water. That should be all you need to do to get it under control.
Yellow bells (Tecoma stans) and its hybrids (i.e., orange jubilee, bells of fire, sparky) are subject to damage from Tecoma leafroller moth caterpillars (Antigastra catalaunalis) which skeletonize the leaves. If you have an otherwise healthy plant, consider co-existing with them. They turn into moths that are important pollinators and food source for other wildlife.
If you feel they are overwhelming your shrub, prune off the worst areas or use the jet spray on your hose to dislodge them. Spraying insecticides, soap, or Bt (Bacillus thuringiensis) is largely ineffective since the caterpillars are tightly wrapped in leaves and protective webbing.
Upcoming Gardening Events in July
While the number of outdoor garden events tapers off in July, there are still numerous gardening classes and activities to attend, many of which are online. There is always something new to learn about gardening!
You’ll find an up-to-date list of gardening-related events in our Tucson Gardening Events Calendar.
If you live in Tucson, be sure to check out these ongoing evening events now through August. (You may have similar festive evening events near you.)
- Tohono Chul’s “Chillin’ at the Chul”
- Arizona-Sonora Desert Museum’s “Cool Summer Nights”
- Tucson Botanical Garden’s “$5 Fridays”
Don’t live in Tucson? Look for online classes. You can participate in these no matter where you live.
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.
Photo Credits
Arizona State University’s Virtual Library of Phoenix Landscape Plants
Miwasatoshi, CC BY-SA 4.0, Wikimedia Commons