Gardening Tips for August

Monthly task lists help to grow and maintain your gardens, indoors and out.

Scan these tips from gardening expert, Melinda Myers, and follow those that apply to your particular landscape to help increase your success while making gardening easier, less stressful and fun.

• Check zinnias, begonias and other annuals for powdery mildew.  This fungal disease looks as if someone has sprinkled baby powder on your leaves.  Proper spacing for improved air circulation and sufficient sunlight will help reduce the risk of this disease.

• Aster yellows can cause green petals, distorted leaves and misshapen flowers on many plants.   There is no chemical control.  Remove infected plants as soon as it is found.  This helps reduce the risk to nearby healthy plants.  Control aphids and leafhoppers feeding on the plants.  These insects carry the disease from infected plants to healthy plants.  Controlling these insects helps reduce the spread of these diseases.

• Harvest blueberries when they are fully colored, sweet and juicy.  Like other berries, store them in shallow containers to prevent crushing the fruit.

• Harvest potatoes as the tops die and tubers reach full size.  Dig carefully to avoid damage.  Gently remove excess soil and store surplus potatoes in a cool, dark location.

• Reduce brown tips on spider plants, dracaenas and prayer plants by keeping the soil slightly moist.  This dilutes the fluoride and chlorine in the water, preventing tip burn.  Or use rainwater, dehumidifier water or distilled water for these plants.

• Lawn insects are more of a problem when the weather has been hot and dry.  Continue monitoring for grubs, billbugs and chinch bugs.  Make sure the insects are present and the damage is severe enough to warrant treatment.

• Try cutting back short-lived perennials, such as blanket flower (Gaillardia) and pincushion flower (Scabiosa).  Late-season pruning will stimulate new green growth and may help extend the plant’s life.

• Black spot may be causing significant damage to your roses by now.  Most fungicides are preventatives and won’t cure what is already infected.  Make a note to start treatment earlier next season if this is a yearly problem in your garden.

• Replenish mulch around established plantings of trees, shrubs and perennials.  Maintain a 2-3 inch layer of shredded bark, woodchips, shredded leaves or evergreen needles around these plants.  Do not bury the crowns or place mulch against tree bark.  This leads to rot and disease.

• Watch for brown leaf edges that can indicate scorch.  Pay special attention to hostas and other shade lovers grown in sun.  Water is not always the solution.  Often the plants are unable to take the water up fast enough to replace what they lose during extreme heat.  Mulch the soil, water properly by moistening the top 6 inches whenever the top 3 to 4 inches start to dry, and consider moving plants to a more suitable location in the future.


• Plan on replacing weatherworn annuals with fall bedding plants.  Purchase pansies, kale and other cool season annuals to spruce up the garden for fall.

• Watch for heat stall in the garden.  Alyssum, lobelia, snapdragons, pinks and French marigolds are a few annuals that stop flowering during extremely hot weather.  Wait for the weather to cool for these plants to resume flowering.  If this is a yearly problem, find a cooler location for these plants.  Next year try planting zinnia, gazania, moss rose and other more heat tolerant annuals.

• Plan to extend the growing season using cold frames, cloches and season-extending fabrics.  A little protection on those first frosty nights can extend your growing season through the warm weeks that always seem to follow.

• Make one fall harvest of rhubarb before the first killing frost.  The stalks are safe to eat and the plant has had ample time to replenish its energy supply.  Cut the rest of the stalks back after a hard freeze.

• Keep pulling weeds and removing insects and diseased leaves as soon as they are discovered. Do not compost pest-infected plant material.

 • Find an area to quarantine houseplants as they move indoors.  It should be in an area with good, bright light, but separate from your indoor houseplants.  Keep plants in this area for several weeks.  Check along the stems and under the leaves for insects.  Control any pests found and continue to monitor.  Once the plants are free from insects, it’s safe to move them in with the rest of your houseplant collection.

 • Do not fertilize your perennial gardens.  Late season fertilization encourages problems with winter survival.  Use this time to evaluate the health and vigor of your plantings.  Make note of those areas that need topdressing or fertilization next spring.  Look for bare areas for adding new plants or planting areas.  Fall is a great time to add new plants or for preparing the soil for new gardens.

• Deer and rabbits continue to feed on roses and other garden plants.  Repellents, fences and scare tactics may provide some relief.

• August is usually the hottest, driest month of the summer.  Check all plantings for moisture stress.  New plantings are your highest priority.  Make sure the top 6-8 inches remain moist, not wet. Check new plantings twice a week and water when the soil begins to dry.  Improper watering is just as harmful as lack of water.  Overwatered plants suffer from root rot and die.  Shallow watering encourages shallow rooting that is more susceptible to drought.

• Plant Autumn Crocus and Surprise Lilies now through early September.  These new additions will bloom for you this fall.  Mix these bulbs with perennials and groundcovers.  Autumn Crocus planted with Vinca groundcover doubles your bloom time.  The Vinca produces attractive flowers in spring followed by the leafless Autumn Crocus blooming in fall.

• Harvest Elderberries throughout the month.  Taste the fruit to check for ripeness.  Pick when the berries are fully colored and juicy.

• Keep planting seeds and transplants of short-season crops that can be harvested before the first killing frost. 

• Check the lower leaves of tomatoes for yellowing and brown spots.  Septoria leaf spot and early blight are common causes of these symptoms.  Remove and destroy infected leaves as soon as they are found.  Fall cleanup, proper spacing, staking and full sun will reduce the risk of this disease.  Regular applications of a fungicide labeled for use on vegetables, can be used to prevent the spread of this disease.  Read and follow label directions carefully.

• Bromeliads are fun, beautiful plants that can brighten up any indoor garden.  Add these members of the pineapple family to your indoor garden.  Grow bromeliads in a bright location.  Keep the soil evenly moist for all but those with Bromeliads that have thick, fleshy leaves.  Water the soil until the excess runs out the drainage hole.  Water again as the top 2 inches begin to dry.

• Mid August to mid September is the best time to repair, replace or start a new lawn.

• Overseed thin lawns.  Creating a denser stand of turf will help reduce weeds, fight pests and improve the overall appearance.

• Check Bee Balm, Garden Phlox and other perennials for signs of powdery mildew.  Look for a white powdery substance on the leaves.  Substitute mildew-resistant varieties for those infected in the garden. 

• Reduce maintenance and improve plant health by creating large planting beds around trees and shrubs.  Or look for bare areas for new plants or planting beds.  Late summer is a great time for adding new plants or preparing the soil for new perennial gardens.

• Finish planting potted Hybrid Tea roses early in the month.  The later you plant, the greater the risk of winterkill.

• Capture and destroy slugs eating holes in the leaves of hostas and other shade lovers.


 Written by gardening expert, Melinda Myers. Melinda Myers is a nationally recognized gardening expert with more than 30 years of horticulture experience. She is a wealth of knowledge and we are pleased to share Melinda’s monthly gardening tips with you!