Summertime in the Southwest can be brutal on plants, and August is perhaps the toughest month of all.

Every Year is Different

Some parts of the region had monsoon rains, some parts did not. This makes it difficult for me to guide you precisely. For some corners of the Southwest, too much rain came all in one event, causing erosion issues. My yard experienced wash-outs of a number of my water harvesting berms. Water can be a strong force of nature!

August Tasks

Plan

Even if you are not inclined to go out and work in the garden, it is a good time to go out and take a wander around the yard and do some planning. Perhaps plan for some planting like an almond tree – looks lovely and feeds you a treat!  Plan ahead for spring wildflowers or spring flowering bulbs.  You will plant those seeds and bulbs in September into October.

Or simply look around to see what might need some changing.  A garden is an ongoing process. 

Plant

August is the last good chance to plant things with tropical genes. This includes cacti, mesquite trees, shrubs such as aloysia, and desert goji, new Bermudagrass lawns, palms, and even young citrus. These plants with tropical genes need ample time get their roots down into the soil during this warm time and well before first frost. There are other fruits with tropical genes that can be planted with care now, like pineapple guava, bananas, and avocado.

Fertilizer

After mid-month, fertilize lawns, palms, flowers, vegetables, citrus, and non-legume landscape plants. Vegetable gardens too. Nut crops can get one last dose of blooming fertilizer.

For those of you that follow my “Fertilize by the Holidays,” this is the Labor Day fertilizer.

Irrigation

Water your crops! Water the nut crops, all fruits, and especially citrus if you don’t get any deep rain. Nut crops especially will benefit from watering if you don’t get rain, citrus are less critical of less water a-in this month because they ripen later. Water deeply to ensure a good crop.

Almost more important than a deep water is a wide water. Yes wide. Apply water well away from the trunk. Above all avoid daily shallow watering right at the trunk. More in Water for Plants

Look Sharp!

For those of you with lawns, Sharpen mower blades. Yes, again. Hurts the grass plants of your lawn less when you mow with nice sharp blades.

For those of you that prune, when was the last time you sharpened those blades?! It’s a nice indoor task to do.

Sharpen your shovels and trowels too. Not knife sharp – but you can save some muscle aches with a bit of an edge. More about this in Tool Care.

Sharp eyes too. Walk your fence-line or walls. Check for spots where hungry wildlife may get in. Gates are especially an issue. If you discover a snake in your yard, it is because you have mice, packrats, or other similar food the snake is tracking with its very sensitive smell organs.

Prune

Finally – August is the one month when you can prune your palms without fear of the palm borers finding tasty palm hearts to eat. If you can, watch you palms for a while before calling the trimming crew. Insect-eating orioles often nest up in under those shady leaves, and their young may not have left the nest yet.

Since August is still a blazingly hot month, make sure the ones doing the pruning leave ALL green leaves, yes, even the ones pointed down, to shade the part of the trunk with the tender palm heart inside. (More on palm care – here)

If your oleander plants have galls, cut affected branches off at least one foot below the galls. Be sure to sterilize clippers in bleach water or rubbing alcohol between every cut. I suggest eliminating the issue entirely by removing the toxic oleander and planting the non-poisonous Arizona rosewood (Vaquellenia californica).

Vegetables

Cut back any over-summered tomato-family plants. This will encourage new growth and possibly some more fruit in fall. Might be for fried green tomatoes if we have an early frost – but it will be a harvest.

Depending on your elevation you can plant a fall vegetable garden.  This is not quite the same as a winter garden.  It is a special – squeezed in – garden season.

Low and Middle Desert consider pumpkin, squash, zucchini, bush beans, and robust seedlings of the deadly nightshades (if you can eat them): tomato, pepper, tomatillo, and eggplant. You can start the seeds indoors now. Middle Desert plant after mid-month, Low Desert, plant after Labor Day.

Upper Desert start your cool season garden including radish, vegetable greens, lettuce, mizuna, spinach, Don’t forget herbs like dill and scallions.

High Plateau and Upper Elevations, a last crop of radish might be able to be grown, but by and large you are putting your garden to bed and considering what cover crop you wish to sow. I have been reading good things about buckwheat.

Flowering Plant Care

Iris can be and divided and transplanted in late August or September.  In fact there are at least 25 plants that can be divided soon.  More in this article on Fall Plant Division. I mention this now because you will need to plan where to put those divisions!  

Summer-tired plants that bloom almost year round need a trim to remove spent blossom twiggyness. Not too severe, just a general “shaping type hair cut” not a buzz-cut. Autumn sage, globe mallow, and desert lavender (Hyptis emoryi) are examples of this.

Trying to say this next correctly is and having trouble finding the words.

Aloysia and other shrubs that bloom in both spring and summer can get the same treatment as autumn sage. These spring plus summer bloomers are not the same as plants that bloom in summer predominantly, the summer bloomers. Plants like the Lovely Leucophyllum.

The fall blooming shrubs should be left alone because any pruning will remove the buds. Isocoma, desert seep willow, and so many more that I am blanking on at this moment.

Find Joy

Hopefully your garden is providing you with some cool enjoyment in early morning and in the evening hours. This is not so difficult if you have a Moon Garden, like one of my Substack followers. She commented, “I love being able to enjoy my garden at night.”

Cover Image: Vines covering an arbor used to create an outdoor office. 

More About Vegetable Gardening

The latest printing is printed in the USA!  I am so delighted!

The Southwest Fruit & Vegetable Guide offers not just growing guides but some of the latest varieties – including ones specifically for raised bed and container growing.  Price is currently more than what you would pay on Amazon – but when you buy from me you get a signed copy!

From the review:

“In this updated 2nd edition of Southwest Fruit & Vegetable Gardening, you’ll find much-needed advice and practical tips on growing an edible garden, no matter which part of the southwestern US you call home.

Profits from the sale of this book go to the Arizona-based Horticulture Therapy non-profit Tierra del Sol Institute.

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