Monitor the landscape for signs of drought stress: premature fall color on trees, leaf scorch, shedding of older leaves, and shoot dieback. Provide supplemental water and water deeply.
Stay alert to plant diseases such as rust and powdery mildew. While they typically won’t kill a plant, they can stunt it or reduce its vigor. For severe damage, apply an appropriate fungicide and remember to follow package directions carefully.
Ornamental Garden
Deadhead garden phlox (Phlox paniculata) before it sets seed. Phlox seedlings, particularly from cultivars, do not come true to parent flower color.
Direct sow seeds in late August or September for early-blooming, hardy cool-weather annuals such as calendulas, Iceland poppies, larkspur, primrose, pansies, violas, snapdragons, stock, or forget-me-nots.
Remain vigilant throughout the growing season for fungal diseases on roses such as black spot. Clean up and dispose of all fallen rose foliage. Fungal spores on any affected foliage that falls to the ground will overwinter in the soil and infect next year’s roses.
Do not prune trees or shrubs at this time of year. Pruning can trigger new growth, which will be too tender to survive cold winter temperatures.
Cut back any remaining day lily flower stalks to keep the plants looking tidy. Also, August or September is a good time to divide day lilies so that they become re-established before the onset of winter.
Order spring-flowering bulbs now while selections and quantities are good.
If annuals are looking tired, but still have some life left in them, shear them back, fertilize, and water them to encourage another round of blooms.
Be on alert for fall webworms and their tent-like silken webs, which appear mid- to late-summer through early fall.
Edible Garden
Harvest tomatoes, eggplants, peppers, cucumbers, and other warm-season crops on a regular basis to maximize crop production.
Snip herbs such as oregano, marjoram, mint, and parsley to stimulate new growth.
Since August is generally very hot and often very dry, monitor moisture levels and water crops deep at least once a week. A layer of mulch helps retain moisture and keeps roots cool.
Cut back chard that was planted in spring to spur it to produce new growth.
Keep weeds under control.
Plant transplants of cold-tolerant crops such as cabbage, kale, collards, cauliflower, mustard greens, broccoli, and Brussels sprouts.
Sow spinach seeds toward the latter part of the month or in early September if the weather is still too hot.
Flea beetles can still be a problem at this time of year, so check for them daily and be prepared to cover susceptible crops with light-weight row covers as necessary.
Lawn
Mow grass during cooler times of the day like early evening. Mowing in the heat of the day stresses the grass blades.
If weather conditions turn hot and dry, lawn grasses may go dormant. To tell if grass is dead or merely dormant, find a brown patch and tug gently on the grass. If it doesn’t easily pull up and appears to be firmly rooted, then it is likely dormant due to drought and will rebound under the right conditions.
If grass was planted this year, its root system may not be robust enough to survive drought conditions. If it is necessary to provide supplemental water to keep the grass alive, water in the early morning to minimize moisture loss. Watering during the heat of the day results in a significant loss of moisture due to evaporation.
