Hello Friends,

We’ve made it halfway through the summer months and will hopefully get much-needed monsoon moisture to help provide relief from the hot, dry weather. During this time, you may notice signs of heat stress in your garden. If you haven’t done so recently, in the morning, observe how your plants are doing. Take note of those struggling to survive the heat and, at the same time, notice which ones are doing well. This information will be helpful when fall arrives, which is the best time to add new plants. To help you, I’m sharing my favorite heat-proof shrubs for clients and in my own garden. You’ll be surprised at their beauty and resilience to our hotter summer temperatures.

While there aren’t many garden tasks in the middle of summer, some should be done to prepare for the monsoon season (even if it is drier than normal). Below, we explore strategies to minimize damage to trees and prevent flooding around your home and how to collect rainwater for later use.  

In our next issue, we will prepare for prime planting season, and I’ll share my best tips for installing new plants to ensure their success. 

Noelle, aka “AZ Plant Lady”
Send your gardening questions to info@azplantlady.com. 

Low to Middle Elevations

Cacti and palm trees can be added to the landscape now. Palms, (excluding queen palms) prefer warm soil temperatures when put in the ground, so summer is the best time to add them. When installing cacti, make sure they are oriented in the same direction as they were previously planted. Many nurseries make a mark on the container that designates which side should face south. Changing the plant’s orientation can result in sunburn and damage. If you don’t know the plant’s original position, wrap the sides with 30% shade cloth until late October when the sun’s intensity is less.

Lightly prune shrubs and ground covers in late summer if they are overgrown. If they have room to grow, leave them alone. However, if plants have become too large for their space, you can clip back up to one-third of their outer growth. At the same time, you can trim wayward branches or stems. Keep it minimal and avoid major pruning, which is best done in spring. 

Check the irrigation frequency of your cacti and other succulents. Mid- to late summer is the most stressful time of year for these plants, as our high evening temperatures interfere with their ability to breathe. Overwatering can add to this stress and often results in their demise. Water no more than every two to three weeks. You can go even longer if they don’t show signs of wrinkling or narrowing. 

Feed citrus trees. For healthy trees and delicious fruit, I recommend applying fertilizer three times per year, around Valentine’s Day, Memorial Day and Labor Day. Use a fertilizer formulated for citrus, and follow package directions on how much to apply. Be sure to spread it over the root zone, which extends toward the outer branches. Lightly rake it into the top 1-2 inches of soil, and water well after applying to help it reach the roots. 

High Elevations

Deadhead roses and perennials to encourage repeat blooms. Cut rose stems back to a quarter inch above seven rose leaves. Better yet, before they begin to fade, bring blooms indoors, where you can enjoy their lovely fragrance. Flowers from plants such as coneflower, coreopsis and daisies, should be trimmed back to the base of the plant once they have dried out to help promote new flowers.

Keep an eye out for damaging insect pests.  Light infestations of aphids (and many other unwelcome bugs) can be managed by spraying them with a strong jet of water every few days. Beneficial insects that will eat them, such as lacewings and ladybugs, usually show up a week or two later. Most plants can handle some damage from aphids with no ill effects, so intervention isn’t needed unless you see signs of curling leaves or the wilting of new growth. Insecticidal soap or neem oil are good choices for controlling larger infestations.

Treat powdery mildew in perennial and vegetable gardens. Look for leaves that have white splotches that resemble baby powder. This is caused by a fungus that harms plants and spreads to others nearby. Remove affected leaves and disinfect your pruning tools to avoid spreading the mildew elsewhere. Spray the remaining foliage with a solution of 1 tablespoon baking soda, half a teaspoon Castile soap (not dish detergent) and one gallon of water. Apply to the top and underside of leaves, which will help prevent powdery mildew from affecting remaining growth.