August is the month when many gardeners in our region dream of moving to cooler climes. Northern gardeners lament the month of January, but we suffer through August’s doldrums instead. But do not despair! There are still several things that you can do in the garden this month.
Prune your oak trees. Oak wilt (Bretziella fagacearum) is a major concern in our region, with red oaks being more susceptible than white oaks. Common red oaks in our region are Southern live oaks (Quercus virginiana, Zones 8–10), escarpment live oaks (Q. fusiformis, Zones 6–10), Spanish oaks (Q. buckleyi, Zones 6–11), Shumard oaks (Q. shumardii, Zones 5–9), and blackjack oaks (Q. marilandica, Zones 6–9). Safe times to prune are when temperatures are over 90°F or under 50°F. Since August falls squarely into the over-90°F category, this can be a good time to prune. I like to save most of my tree pruning for the cold months just for my own comfort, but sometimes I have some pruning that just can’t wait until winter, so August will suffice. No matter what time of year you are pruning, remember to paint all pruning cuts made on oaks to protect against oak wilt. Pruning cuts on other species do not need to be painted.
Collect seed from summer-blooming plants. Don’t forget to collect seed from the dried, spent flower heads on your summer-blooming plants. I end every summer with paper bags full of dried flowers from perennials such as purple coneflower (Echinacea purpurea, Zones 3–9), black-eyed Susan (Rudbeckia hirta, Zones 3–9), Engelmann daisy (Engelmannia peristenia, Zones 4–8), and chocolate flower (Berlandiera lyrata, Zones 5–11). Learn more about collecting seeds here.
Lightly prune roses for a flush of fall blooms. August and early September is when roses need their second, lighter pruning of the year. Remove dead or unproductive twigs as well as any canes that cross. Avoid removing foliage this time around, and focus on the dead woody material. Get tips on pruning different types of roses here.
Water deeply and infrequently. This advice is good all year round, but it becomes especially crucial in August. How do you know when you need to water? Stick your finger into the earth around your plants’ root zones, and check for moisture about 3 inches down. If it’s dry, make sure to provide enough water to reach that depth. Most plants will not be putting on much growth this month, but sufficient water will keep them alive until cooler temperatures allow them to thrive again.
Don’t plant anything this month, except… Because of the heat, August is not a good time to plant most plants. I generally avoid planting ornamentals this month, particularly trees or large shrubs. There are, however, a few things that you can plant in your vegetable garden that can take the stress of August: beans, corn, cucumbers, Southern peas, summer and winter squashes, and surprisingly, potatoes!
—Karen Beaty is a horticulturalist at the Lady Bird Johnson Wildflower Center in Austin, Texas.