August Gardening Tips

There once was a garden in Maryland
Whose plants weren’t looking to grand
They all cried for rain
But it was totally in vain
Because Mother Nature wouldn’t lend them a hand

Outdoor Garden and Yard Tips

• August is frequently a dry month. If needed, water newly planted trees and shrubs. Allow the water to soak into the surrounding soil and the root ball.
• Fall webworm is a late summer caterpillar 1-2 inch long and hairy caterpillar. It creates large tent like webbing on the ends of branches of various shade trees and shrubs. Unsightly but causes little damage. Numerous caterpillars, including leafrollers, orange striped oak worm, green-striped maple worms, oak skeletonizers, and sawflies are feeding on various shade trees. No controls are necessary. If you see saddleback caterpillars or other stinging caterpillars, leave them be.
• Avoid mowing your lawn during extreme dry and hot weather. Mowing wounds grass blades creating more surface area for plant moisture to escape.
• Brown patch is a common fungal disease of tall fescue lawns that creates thin, brown areas. Grasses will green up and recover in the fall. No chemical controls are recommended. This disease is typically worse on over-fertilized and irrigated lawns.
• Remove hosta leaves that are yellowing or scorched (brown leaf margins). In many cases, this is caused by a combination of hot, dry conditions, or diseases like alternaria and anthracnose (Colletotrichum). If disease related, leaf removal will help to slow down disease progression.
• Southern blight, a significant soil-borne disease, is promoted by hot and humid weather. It attacks a wide range of annuals, groundcovers, and perennials including thyme, coneflower, coreopsis, and black-eyed Susan. Affected lower stems turn brown or black, foliage wilts and plants will eventually dry up and die.
• Submit a soil sample for testing if planning a lawn renovation project in the fall.
• European hornets sometimes strip the bark off shrubs (especially lilac) and trees. This behavior rarely does harm. The European hornet is a large yellow and brown hornet that nests in cavities in trees, stumps, wood piles, sheds, etc., and feeds on insects. Unlike most other wasps and hornets this one is a night flyer.
• Try to ignore hornet, bee, and wasp nests found outside, especially if they are located in a tree or an isolated area. These are beneficial creatures that will not sting unless disturbed or provoked. However, if a hornet or yellowjacket nest is a threatening nuisance such as under your deck or near a door you can destroy it with a labeled wasp and hornet spray at night. Read and follow all label directions.
• Roses weakened or stressed by the hot dry summer weather are incredibly vulnerable to mites, aphids, and Japanese beetles. Japanese beetles can be controlled by knocking them off into a cup of soapy water. A low population of aphids does little damage and can be washed off with a steady stream of water from your hose. Remember to let the water run for a few moments to run out the hot water from the days sun before spraying plants. Aphids have many natural enemies including parasitic wasps, ladybird beetles (ladybugs) and larvae, and green lacewing adults and larvae. These natural enemies help keep aphid populations under control.
• High heat and humidity encourages powdery mildew in perennials. Avoid overhead watering. Remove diseased stems and leaves. Make a note in your garden log for next season to move affected plants further apart to increase air circulation between plants.

Photo: Scout squash plants for squash vine borer. If you notice a suddenly wilted squash plant inspect the vine for signs of holes and frass (moist greenish or orange sawdust like material). The stem near the entrance hole will feel mushy. The borer can be controlled in two ways. For active borers, make a vertical slit upward from where frassis observed. Use a razor or sharp knife and cut half-way through the stem. Remove and kill borer. Mound soil over the wound to induce supplemental rooting. However if there are several entrance holes all over the plant it is recommended to remove the plant and place is a black trash bag and put it in the sun for a few days. This will kill the squash vine borer larvae. Do not throw the plant in your compost pile. Photo credit: Rachel Rhodes.

Vegetable Garden

• Harvest tomatoes when they first change color and ripen them on a kitchen counter.
• Brown and green Southern stink bugs are active on tomatoes and peppers. They feed on the fruits producing a yellow or white “cloudy spot” directly under the fruit skin. These spots become hard but can be cut out with a sharp knife and won’t affect flavor. If stink bugs are a problem, try handpicking first or spraying pyrethrum.  The spray must contact the stinkbugs to be effective.
• Harvest and preserve tarragon, rosemary, basil, sage, and other culinary herbs. Fresh basil leaves freeze well in plastic bags that can be sealed. Pick individually, and dry indoors, or hang the stems a dry, semi-shady room. Store dry leaves in air-tight jars. Herb leaves are most intensely flavored right before the plant blooms.
• Remove and dispose of all rotted or dropped fruits and foliage from trees, vines, and bushes. This will help reduce the overwintering of diseases and insect pests that will attack your fruit plants next season.
• Plant a late crop of basil, cilantro, and dill and a last crop of snap beans the first week of August.
• Plant cool season crops, including spinach, lettuce, carrots, beets, broccoli, cauliflower, Chinese cabbage, turnips, kale and mustard. Keep seedlings moist and mulched.  Order garlic, walking onions, and shallots for fall planting.
• Grass clippings and spent plants from the flower and vegetable garden provide a good source of high nitrogen green materials for the compost pile. Fallen leaves and old straw mulch are good sources of high carbon brown materials. Shred your materials with a lawnmower, string trimmer or machete to speed-up the breakdown process. Keep sticks, roots, and woody stems out of your compost pile. They take too long to breakdown and make it difficult to turn the ingredients. Water your compost pile weekly when you water the garden and turn it regularly.

Rachel J. Rhodes, [email protected] is the Horticulture Educator and Master Gardener Coordinator for the University of Maryland Extension in Queen Anne’s County. She is one third of the Garden Thyme Podcast. The Garden Thyme Podcast is a monthly podcast where University of Maryland Extension Educators, help you get down and dirty in your garden, with timely gardening tips, information about native plants, and more!

For further information, please visithttps://extension.umd.edu/queen-annes-county/master-gardener-home-gardening  or see us on Facebook @ https://www.facebook.com/QueenAnnesCountyMasterGardeners or listen to The Garden Thyme Podcast at:  https://www.buzzsprout.com/687509

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