If you want to do any planting in July, do it early in the month and make sure it is a tropical plant or succulent that can take the heat. Just because it is thriving in a pot at the nursery does not mean it will withstand transplanting in the heat of summer. You will need to keep the new transplants well watered all summer even though they may be drought tolerant once established.
Determine which plants may need extra water this month. A long slow soak will keep established shrubs from becoming susceptible to problems in the months ahead and will encourage deep roots. Be sure there is enough mulch to keep the soil cool and let it dry out between watering. Some plants, such as impatiens, may need to be watered daily. Grouping plants that require more water during the summer will make it easier to keep up with their requirements.
This is a good time of year to think about adding plants in the fall to provide more shade in the yard in the future. Dappled shade or filtered shade can have a cooling affect, cut down on water requirements and still give many plants enough light to thrive and bloom. Keep summer blooming perennials deadheaded and tidy. Cut them back or sheer them after heavy blooms to encourage another round of flowers. Pinch back shrubby perennials to encourage blooms and discourage leggy stems. A midseason dose of fertilizer will keep them going through fall.
Plants that are stressed during the hot weather can become susceptible to insect damage. Occasionally hosing them off in the early morning to remove dust and debris will also knock off insects and revive plants. On extra hot days providing a few hours of relief from the hot sun by positioning an umbrella over young plants that are not yet established or plants prone to wilting can give them some much needed relief.