Water Herbs Carefully
Many herbs look rangy or die back somewhat at this time of year. Don't be tempted to overwater, which won't help them recover. Herbs don't like wet feet. Water deeply to a depth of 12 inches. Wait to trim back dead material after the heat subsides.
Wash Dusty Plants
Spider mites thrive in the dusty conditions created by monsoon thunderstorms. Spray off plants with a blast of water from the hose in the early morning hours. Spider mites are usually noticeable by the fine webbing they create on foliage.
Roses are susceptible to iron chlorosis, a yellowing caused by the plant's inability to absorb iron in the soil. Iron chlorosis shows as yellowing leaves with green veins. (Nitrogen deficiency shows as the entire leaf yellowing. Usually older foliage will yellow first.) Apply a chelated iron source and water it in well to a depth of 2 feet. Replenish mulch if needed and check for spider mites.
Palms actually thrive when planted in the midst of summer heat. If you're contemplating palms, now is the time to get them in the ground so their root systems can establish before the cool soil temperatures of winter.
Note Citrus Fruit Split
If fruit is splitting, it is caused by insufficient watering earlier in the season. Tough rinds can't expand to keep pace with the expanding fruit and they split. There's nothing that can be done at this point. Make a note to monitor watering next year as fruit starts sizing up.