written & photographed by Scott Millard
Summer is the season to maintain your plants through several months of warm, often hot temperatures. Slow and steady watering counters the effects of intense heat and sunshine. Mulch, preferably organic, is your plants’ best friend: It tempers the toll of heat gain and moisture loss in the soil’s upper layers. The margin for gardener error is slim this season, and new plants set out in spring are particularly vulnerable. Check plants often for signs of heat stress.
MAY
Planting
Remove tired petunias, violas, and pansies (cool-season annuals) and replace with their warm-season cousins: periwinkle, zinnias, portulaca, red and blue salvia, and marigolds. Renew the soil in beds and containers before planting by adding organic amendments and ammonium sulfate at the rate of one pound for every 100 square feet. Set out seedlings of warm-season veggies— eggplant, squash, peppers, and melons. Even if you planted some of these in late April, succession planting will stretch out your harvests.
Watering
As mentioned, watering is the primary gardening activity for the next several months. Check the soil for moisture before plants show signs of needing water. Fruit-producing plants such as peach trees, citrus, and grapevines should receive regular waterings or plants may drop flowers and developing fruit.
Care
Mulch Mulch is a material applied in a layer over the root area of plants. A few inches of mulch help cool the soil and reduce evaporation. A layer of almost anything helps, including gravel or stones, but organic mulches such as compost, ground bark products, and lawn clippings also decompose to improve the soil.
Insect pests Populations of insect pests explode as temperatures warm and as plants produce tender new growth. Spider mites thrive on the undersides of leaves, sucking plant juices. Stippled, yellowing leaves and spiderlike webbing are telltale signs. Wash leaves clean with water and spray infested areas with insecticidal soap.
Protection Birds and other animals may enjoy your harvests before you can if you fail to protect your plants. Cover fruit trees entirely with netting. A sturdy PVC-pipe framework, staked to the ground and covered completely with wire or netting, will keep most small animals out of vegetable plots. The sun can also be a villain, burning ripening tomatoes and peppers. Cover developing fruits with row-cover materials available at many nurseries.
Fertilizing If leaves of citrus plants are pale green, fertilize late in May with a complete citrus food. Likewise, fertilize and water roses well. Warm May temperatures bring Bermuda grass out of dormancy. Feed with complete lawn fertilizer or ammonium sulfate.
JUNE
Planting
In June, temperatures begin to soar, so consider holding off major plantings of trees, shrubs, and perennials until September or October.
Palms The grasslike roots of palms establish best with heat, so June and July are good months to plant new palms from containers, or to transplant existing young palms. Wait until soil temperatures warm to at least 75°. Water carefully after planting, and mulch soil to conserve moisture.
Vegetables Continue succession planting of warm-season vegetables every 3 weeks or so to extend harvests. Sow seeds of squash and melons directly in the garden—the warm summer soil causes seeds to germinate rapidly.
Watering The high temperatures and low humidity typical of June weather can quickly stress plants. A daily watering patrol (morning is best) around the landscape helps you spot thirsty plants.
Care Prevent weed seeds from germinating. Apply a pre-emergent spray in mid- to late June before July’s summer rains kick off the summer weed crop.
JULY
Watering
Typically, from the first part of July until late September, some areas of Tucson are blessed with rains from the summer storms we call monsoons. But these storms are highly localized—just a mile or two from a downpour it may remain completely dry. Also, the rains often fall fast and furious, resulting in runoff. Moisture fails to soak into the soil to benefit plant roots. Check soil moisture to be sure.
Care
Mulch to ease the pain Refresh the organic mulch you applied in May. (Winds and high temperatures can cause it to blow away and dissipate.) A layer up to 3'' thick works well. Keep mulch away from the trunks of trees, especially citrus.
Pests, large and small July is one of the most active times of the year for pests, and July is the most common month to see Tucson’s infamous palo verde beetles. Destroy them if you can, before they can lay their eggs at the base of palo verdes and other desert trees.
Inspect plants for more typical pests at least once a week (vegetables and fruits every few days) during the next few months. Grape-leaf skeletonizers attack grape leaves in waves throughout summer. Watch for slow-moving black moths as they fly around your vines. They want to lay their eggs on leaf undersides. Black-and-yellow caterpillars, with voracious appetites for grape leaves, follow. Clip and destroy infested leaves.
Check ties on vines Long, hot summer days in combination with regular moisture can cause plants to grow rapidly. Loosen or remove plant ties on stakes of young trees and on vines to prevent serious damage.
Feed lawns and landscape plants Regular summer waterings wash nutrients, especially nitrogen, out of plants’ root zones, especially with lawns. Apply ammonium sulfate or other similar high-nitrogen fertilizer.
Scott Millard is the author and editor of more
than 30 gardening books.