August can be a light work month in the garden, assuming you have repaired water leaks and kept the weeds, diseases, and pest insects to a manageable level. The main job this month is to conserve water in every way you can and plan on ways you can make your garden more drought resilient. But there are a few tasks for those of us who simply must do some gardening:
PLANTING: It's time to plant seeds for cool season vegetables: Asian greens, broccoli, cabbage, cauliflower, leek, lettuce, pea, spinach, and Swiss chard. I love planting cool season seeds in hot weather because it reminds me that autumn will arrive someday. You can also direct plant another crop of beans. For everything else, wait until the weather cools down or plant in the shade.
MAINTAINING: Avoid over-watering. Some plants, like citrus, require even moisture and must be watered regularly. Other plants, like most California native, Mediterranean, and desert-origin species can manage on less water. Don't require all of your plants to grow and flower in a hot dry month. If your garden is less than three years old, however, you cannot expect the plants to be tolerant of drought. They will continue to need extra TLC until their roots are established. Deep soaking and occasional extra sprinkles for a few plants is the best practice. If you live in a fire prone area, keep your plants watered so they will help slow down wildfires and reduce flying embers.
Add mulch if you haven't yet. Wood or rock mulch holds in water and regulates soil temperatures, making for healthier plants year-round
Spider mites love dusty plants. If you see cobwebs, it's time to hose off the plants. In gardens with drip irrigation, this is a big problem, because overhead sprinklers aren't washing plants off. Follow your water district's guidelines, but go ahead and wash your plants off in the cool morning or after the sun has set. Avoid overhead water if it's windy.
Divide your iris if you haven't already done so. Prune apricot, olive and oleanders, but avoid pruning so much you get sunburn on newer branches. Continue to deadhead roses and remove suckers and unwanted branches. Open rose bushes up to increase air circulation through the shrub. Continue to prune hedges. Keep your pruning tools clean and sanitized. Clean up fallen fruit. Support heavy, fruit-leaden tree branches. Remember to use BTi anywhere there will be standing water, even in plant trays, to avoid mosquito breeding.
This is a good summer to skip the fertilizer, especially high-nitrogen products. Let everything rest a little, including yourself, and let's all keep our gardens healthy but recognize they may not be the showcases they are in wetter years.
If you spray with post-emergent broad-spectrum herbicides, apply it when the temperature is about 85 degrees Fahrenheit and when there is no breeze, to avoid phytotoxicity and vapor drift. Using a product with surfactant is important to improve penetration on toughened summer weeds. Towards the end of the month, you can start using a pre-emergent to impede germination of cool season weeds. If you have only a few weeds, hoe or dig them out instead of spraying, or investigate where the water supporting the weeds is coming from and make a change in your irrigation practices if you can.
CONSERVING: Will this finally be the year you stop watering that thirsty lawn? Switch to a better alternative like hybrid Bermuda or Val Verde Buffalo grass. Or reduce the size. Or replace the lawn with a low-water-use mixed planting or ground cover like Kurapia (a sterile Lippia nodiflora cultivar.)
The first step in managing diseases and pest insects is identification. That's so you don't accidentally do more harm than good. A good website to consult is: http://ipm.ucanr.edu/PMG/menu.homegarden.html.
Ornamental plants can tolerate some insect damage and those insects can be bird attractants (food). The exception is Argentine and other non-native ants; control those throughout the garden with ant bait products, switching the active ingredient every few months.
It's okay to leave flowers on native plants. Finches and other birds will thank you. If you want to attract more birds and pollinators, it's fine to be less fussy about trimming every plant and removing every brown stem. I invite you to push your own boundaries, to improve the efficiency and usefulness of the garden, and to share it a little more. It's less work too.