Summertime in the Southwest can be brutal on plants, and August is perhaps the toughest month of all.
Every Year is Different
Luckily for many of us, July 2021 brought monsoon rains, including up to 6 or even 8 inches in some areas. For some corners of the Southwest, too much rain came all in one event, causing erosion issues. On my little acre, we experienced wash-out of a number of the water harvesting berms. They are being rebuilt more sturdily following the principles discussed in Brad Landcaster’s excellent book, “Rainwater Harvesting.” (Review of the book on Gardening With Soule’s “Library” page.)
Hopefully your garden is providing you with some cool enjoyment in early morning and in the evening hours. Especailly if you have a “Moon Garden,” discussed a few weeks ago – here.
Anytime During August
August is the last good chance to plant cacti, mesquite trees, 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.
Fertilize lawns, palms, flowers, vegetables, and non-legume landscape plants, during August. Nut crops can get one last dose of blooming fertilizer. Wait until after Labor Day to fertilize citrus.
Water nut crops, all fruits, and especially citrus trees widely – well away from the trunk. Water deeply to ensure a good crop. Avoid shallow daily watering. Nut crops especially will benefit from watering if we don’t get rain.
General Care for August
Sharpen mower blades. Yes, again. Hurts the grass plants of your lawn less when you mow with nice sharp blades.
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 tongue.
Finally – August is the one month when you can prune your palms without fear of the palm borers finding tasty palm hearts to eat. Since it is still a blazingly hot month, make sure the workers 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 you can, watch your 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.
If 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 (Vauquelinia californica).
Look for Chlorosis – Yellow Leaves
July rains often bring August chlorosis. Plants with paling, often yellow, leaves but with green veins are suffering from the inability to take up the iron that is rich in our desert soil. Books written for Back East call this iron-deficiency and tell you to add iron. DON’T waste your money adding iron! Our soils are alkaline and the plants are showing alkaline-induced-iron-chlorosis.
Quick treatment for chlorosis in the Southwest is 1 cup vinegar in 4 gallons of water and use this mix to water plants with. Chlorosis may clear up within 2 weeks. Sadly, it will reappear as alkaline soil molecules do migrate. Plus our irrigation water is alkaline.
Long term treatment of chlorosis is to add compost to the soil and add coffee grounds or other soil acidifiers on a regular basis. Susceptible plants include roses, plus non-native fruit trees like citrus and apples. More on citrus care in this article – here.
Tasks After mid August
Plant a fall vegetable garden with pumpkins, squash, zucchini, bush beans, and robust seedlings of the deadly nightshades (if you can eat them): tomato, pepper, tomatillo, and eggplant.
Cut back any over-summered tomato plants. This will encourage new growth and fruit in fall.
Iris can be and divided and transplanted in late August or September.
As always, enjoy!
More about overall care of your land and landscape in this book: Month by Month Gardening for Arizona, Nevada, and New Mexico (Cool Springs Press). This link is to Amazon and if you buy the book there the Horticulture Therapy non-profit Tierra del Sol Institute will get a few pennies – at no extra cost to you.
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The El Sol newsletter can help with bite-sized bits of information.