Summers are brutal in the southwest desert areas of the USA. It is tough on gardeners who really want to be outside and hard on the plants. Desert plants have adapted to the high temperatures, low moisture and intense light but other plants will need a little extra protection and care to make it through the extremes.
If you can even bear to go outside in the month of July there are some garden tasks that can be done to keep the garden growing and from getting out of hand. The best times to go out are very early in the morning or just before sunset.
Irrigation and watering is best done in the early morning hours but spot watering with cool water during the day may be needed to prevent root death. Run the hose onto an area without plants until the water is coming out cool. The water in the hose can reach very high temperatures especially when it is in the sun and can burn plants and animals.
Move potted plants into shaded areas that allow a few hours of early morning sun. Pots that get direct sun during the day absorb a lot of heat and can kill plants and dry out quickly. Overwatering in pots can also drown roots and encourages root disease and rot.
Recommendations for July from ‘The Desert Gardener’s Calendar’ written by George Brookbank are summarized as follows along with additional comments and tips from my experiences.
Continue with soil sterilization under plastic, plant corn, squash, black eyed peas, Tomato seeds. Purchase or order cool season vegetable seeds to plant in protected seedling trays for Fall planting.
Mature Tomato plants that are suffering now can have about half of the top growth cut back. Brookbank recommends covering them with a white sheet after cutting to protect them from the sun. Cherry tomatoes will continue to set fruit so may not need pruning.
If you are going to use fertilizer in the garden in July, water the soil with about half of normal irrigation first then add the fertilizer with the rest of the irrigation. Save dry fertilizers for cooler months and use liquid fertilizers. If there is concern about burning plants with fertilizer, dilute in half or less and apply over several waterings. More fertilizer is not better and if less is applied more can be added again as needed.
Don’t prune or trim most plants this month. Dead branches or stems of course can always be removed any time of year. Light trimming of stray branches to keep shape is ok but heavier pruning exposes bark and inner leaves to sun damage.
Some garden pests active in July are Grape-leaf skeletonizers, Leafhoppers, Palo Verde borer Beetles, Leafcutter bees, Green Fruit Beetles, Nematodes, Tomato Hornworm and Leaf-Footed plant bugs.
Cucumbers will start to decline and the fruit will become bitter. Armenian cucumbers will continue to do well and should be picked regularly when about 2 inches in diameter or will become very large quickly.
Fruit split may occur on any fruit trees that are still producing if there are heavy rains. But it is a small price to pay for the benefits of summer desert rain. Damaged fruit can be removed to prevent the attraction of flies and leaf-footed bugs.
Protection from birds may be needed for grapes, tomatoes, apples, peaches or figs. Use paper bags on grape bunches and bird net on trees. If there is an abundance of fruit it is nice to be able to share it with nature too.
Prepare rain barrels in case we get lucky and have a quick summer storm. A few large trash cans or buckets to set under the downpour under eaves will give a few days of the best water for indoor and outdoor plants. Don’t collect water that has run off of oily streets or paved areas.
Expect sunburn on leaves and fruits unless measures are taken to protect susceptible plants with shade cloth. And of course the gardener should protect themselves from sunburn and heat stroke. Drink plenty of liquids, work in shade if possible and avoid the sunniest hottest part of the day.
July is the hottest month for Vegas and triple digit temperatures are a common occurrence. High temperatures can also be detrimental to motorized garden equipment. If it must be used take breaks regularly to keep motors from overheating and seizing up. Those who have a pool in their yards can garden a little and take a dip to cool down.
George Brookbank was an Extension Agent for the University of Arizona and lives in Tucson, Arizona. He has authored several desert gardening books that should be available for purchase at nursery centers or at the local libraries for borrowing.