Ask a Master Gardener: May/June 2016


May 9, 2016

Ask a Master GardenerIssue 18: May/June 2016

Have a question about your garden? Submit it at or
You can also call the Pima County Master Gardener Plant Clinic at 520.626.5161.

How can I help my garden survive the high heat and aridity of the Sonoran summer?

In May and June each year, we often receive questions about damage to edible plants related to the effects of seasonal high heat and aridity. While we can certainly offer advice to aid plant recovery, what if you could get a lead on these issues and deal with them early enough to prevent serious damage? You’ve probably heard the saying, “An ounce of prevention is worth a pound of cure”—in the garden those words are golden. As we enter our foresummer drought period, it’s an important time to be present in our gardens.

The way to do this is very simple, and pleasant. It only requires that you take a refreshing walk around the garden oasis you’ve created and communicate with your plants. No, not a literal dialogue that will have neighbors turning their heads, but just a daily look-see in this active season.


Read Your Plants.

With a regular daily walk around, you’ll be surprised at how well you can pick up early changes in the condition of your plants. Look for hydration. Ideally plants are turgid in the morning, slightly wilted in the afternoon, and regain turgidity in the evening. Not so? Then water the soil, not the plant, to a depth of at least 12 inches. Adjust your watering schedule as necessary, and nip dehydration in the bud. Look for nutrient deficiencies. Do leaves have increasing yellow coloration or green veining? Evaluate first, then counter with iron, zinc, manganese, or nitrogen, if necessary. Look for signs of pest damage. Do leaves, stems, or root systems show damage? Are there visible signs of insect or animal pests? Use natural pest control methods when possible; avoid chemicals in vegetable gardens.

Do you see any bacterial, viral, or fungal activity on your plants? Use less toxic controls when possible; avoid chemicals in vegetable gardens.

Check your Plants’ Microenvironments.

Check soil hydration. Push a fingertip into the soil to check that it has some give and consistency. To check further, roll a bit of soil in your hand, squeeze it between your thumb and forefinger, and try to form a ribbon. Is it dry and crumbly? Consider upping the water.

Check sun, shade, and wind. Location is a key factor in successful plant growth—too much or too little sun or shade or direct exposure to winds can be a significant factor in wilting and loss of vigor. Know your plants’ sun, shade, and wind requirements and limitations before planting and choose a location accordingly.

Use 30 to 40 percent density shade cloth during summer heat (shading is less critical for landscape plants). Shade cloth creates a beneficial vegetable plant microclimate by moderating intense sunlight and heat during our desert summer. You can make an inexpensive shade-cloth frame from plastic pipes and zip ties. Leave at least a few inches of air circulation spacing around plants so you don’t create a heat trap.


Have you added mulch? Are you fertilizing soil?

For exposed plants, especially in pots, add mulch to reduce heat absorption, help control weeds, slow down evaporation, and (over time) add nutrients. Organic mulch ingredients for edible plants include compost, shredded tree bark, straw (free from weed seeds), pine needles, and dried leaves.

Before adding mulch, moisten the soil. Do put mulch around plants (and in between and down rows), but don’t put it right up against the plants themselves (stems, leaves). Check mulch throughout the season and replenish as it breaks down and settles.

Are you fertilizing soil as necessary? On a calendar, mark down plant-specific fertilizing information, including when, what, and how much. There is no one-size-fits-all for fertilizing. Use the right combination for the right plants and follow manufacturers’ directions. Remember that over-fertilizing can lead to problems like salt burn or green leafy growth at the expense of fruit, and can attract unwanted insects.

Finally, keep a garden log for plants and locations. List important highlights, including dates, actions, amounts, pest and disease issues, growth results, harvests, and your observations. You’ll find this is very helpful for future garden management and planning. Keeping in touch with your plants throughout the week will pay large dividends throughout the season.

  • If selected, your question may be featured in an upcoming issue of Edible Baja Arizona magazine or on our blog.

Previous Post

Farm Report:
May/June 2016

Next Post

Gardener Q&A with Gary Gholson