Trees, Shrubs, Perennials and Annuals:
Although potted plants can be planted anytime of the year, fall is still the best time to plant hardy trees, shrubs and perennials. Cooler temperatures and lessening light intensity mean less stress for the plants. Root growth will continue while soil temperatures remain around 50 degrees Fahrenheit and above. Now is a great time, transplant as well. As always, be sure to take into consideration the mature size of trees and shrubs as you decide what to plant.

It’s also time to be thinking about changing out your warm season annuals for cool season ones. Think about different color schemes using reliable bloomers such as violas, pansies, snapdragons, sweet alyssum, and dianthus. For foliage accents try ornamental brassicas, dusty miller, and herbs that prefer cooler temperatures such as parsley, dill, fennel and cilantro.

Soil Testing:
If you haven’t already done it, now is the time to prepare your vegetable gardens for next spring. Be sure to have your soil tested if you haven’t done it in the past few years. Commercial growers test every year because lime application to correct pH is critical for plant growth. Every part of your yard can benefit from a soil test.

For more information on soil testing please visit:
https://hgic.clemson.edu/factsheet/soil-testing/
https://www.clemson.edu/public/regulatory/ag-srvc-lab/soil-testing/index.html

Lawns:
The time for pre-emergent herbicide applications for lawns begins this month. Time your application after there have been at least four consecutive nights where temperatures were between 55- and 60-degrees Fahrenheit. Look for temperatures to start dropping around the middle of the month

For more information on weed management in lawns please visit:
https://hgic.clemson.edu/factsheet/managingweeds-in-warm-season-lawns/

Disease Management:
In the best-case scenario, plants in your landscape that are susceptible to diseases (common ones are Cercospora, anthracnose, powdery mildew) would have been sprayed with a fungicide before Hurricane Dorian and the heavy rainfall it brought. Even if that was done, another fungicide application should be applied 7-14 days after that first application. Read the product label to be certain how soon you can make another application.

For the month of August gardeners should focus on continuing to monitor for pests and diseases. Our Landscape Manager, Drew Stevens, recommends paying special attention to hydrangeas that may need fungicide applications to manage cercospora leaf spot and anthracnose. Gray leaf spot and chinch bugs frequently show up in St. Augustine (or Charleston) grass by August. Pests that have recently been brought into the nursery for identification are mealybugs on sweet grass and bamboo; also, root rot on boxwoods. Make that last yearly application of fertilizer to turf (if not done already) and pay close attention to irrigation needs. Continue to feed and groom summer annuals but start planning for cool season ones.

More on Irrigation:

Last August we experienced almost three weeks of daily rain at the nursery. That amount of rainfall can do a lot of damage to plants in pots especially with regards to root rot. If your soil does not drain well, plants in the landscape can suffer too. This year’s rainfall pattern for August could be very different so it’s imperative that you know what to do in any given rainfall scenario. Probably the most frequent questions that we receive at the nursery are about how much water or irrigation is enough. Most folks have difficulty in understanding how complex the answer can be.

When I first began working for Extension in 1996, the general rule of thumb was that plants in the landscape need, at least, 1 inch of water per week. That amount is still used but occasionally I’ve seen 1½ inches of water recommended. So, one way of answering the question of how much is enough is to simply set an irrigation system to supply 1-1½ inches of water per week. There are problems with using a general rule though.

Plants typically don’t have the same evapotranspiration rates (water loss through leaves) throughout the year. For deciduous plants that have dropped all their leaves for winter there may be no water movement at all. (If you ever wondered why certain places become waterlogged or boggy in winter, look around to see how many deciduous trees are nearby. In the summer they pull lots of water from the soil and none in the winter.) Some soils retain water better than others. A clay soil will hold water better than a loamy soil and both have a higher water holding capacity than a sandy soil.

Some plants are more xeric than others and may not need supplemental water at all; others may be especially water loving. With some plants such as turf, Extension specialist recommend waiting until the grass is slightly drought stressed before irrigating. The grass should have a blue-gray tinge, or you can see your footprint after you walk across the lawn before you irrigate. For some plants, though, waiting until they show symptoms of drought stress is not an option.

Below is a list of things that you can do to try to be more efficient and effective with your water applications:

• Group plants in your landscape according to water needs
• Use drip irrigation where possible
• If you have an irrigation system, know exactly how much water it puts out
• Use the can method for above (see Clemson HGIC 1802 factsheet below)
• Try soil moisture sensors (the human finger works really well)
• Mulch, mulch, mulch

Clemson’s HGIC website has a series of factsheets on irrigation that can walk you through many aspects of managing water in your landscape. Below is the series on Irrigation Management. There is also a series on Landscape Irrigation Equipment that you can search for at: https://hgic.clemson.edu/

Factsheet 1800, Landscape Irrigation Part 1: Water in the Landscape
https://hgic.clemson.edu/factsheet/landscape-irrigation-management/

Factsheet 1801, Landscape Irrigation Part 2: Determining When to Irrigate
https://hgic.clemson.edu/factsheet/landscape-irrigation-management-2/

Factsheet 1802, Landscape Irrigation Part 3: How Much Water?
https://hgic.clemson.edu/factsheet/landscape-irrigation-management-3/

Factsheet 1803, Landscape Irrigation Part 4: Winter Irrigation and Winterizing
https://hgic.clemson.edu/factsheet/landscape-irrigation-management-part-4-winter-irrigationwinterizing/

Factsheet 1804, Landscape Irrigation Part 5: Irrigation Time of Day
https://hgic.clemson.edu/factsheet/landscape-irrigation-management-part-5-irrigation-time-ofday/

Factsheet 1805, Landscape Irrigation Part 6: Soil Type and Irrigation Frequency
https://hgic.clemson.edu/factsheet/landscape-irrigation-management-part-6-soil-type-irrigationfrequency/

Lawns:
A mid-summer fertilizer application can be made on Bermudagrass, St. Augustine (Charleston) grass and Zoysiagrass lawns. Apply .5-1 pound of actual nitrogen per 1000 ft². Preferred formulations are a slow release form of a 15-0-15, 16-4-8 or 12-4-8. Be sure there is adequate moisture available to move the fertilizer off the grass and into the soil. If your lawn is suffering from compaction now is the time to aerate it. Core aeration, using a sod-coring tool or a core aerating machine, is preferable to using a tool with tines to punch holes in the lawn. The core tool will remove pieces of sod that can then be broken up and raked over the top of the lawn. Core aeration will create more pore space for water movement and healthy root growth. Again, be sure that adequate moisture is available for the newly forming roots.

For more information on aeration please visit:
https://hgic.clemson.edu/factsheet/aerating-lawns/

Trees and Shrubs:
Trees and shrubs can also now receive a second, lighter application of fertilizer than the one applied in the spring. If your plants appear stressed or diseased, a fertilizer application may only stress the plant more. So be certain there is adequate moisture in the soil for new root growth and the plant appears healthy. If you haven’t mulched your plantings think about doing it now. Be sure the soil is moist. Spread the mulch evenly over the area around the plants to a depth of 3-4 inches. Be sure that the mulch is placed a couple of inches away from the stem or trunk of each plant. If the trees and shrubs are surrounded by lawn which has been fertilized, an application may not be necessary.

To calculate how much fertilizer is needed please visit:
https://hgic.clemson.edu/factsheet/fertilizing-trees-shrubs/

Annuals and Perennials:
Annuals especially need fertilizer applied in multiple doses over their long period of blooming. Perennials need adequate nutrients to be sure they come back strong the next year. If you didn’t have your soil tested, consider doing that now. Otherwise apply a slow release fertilizer, such as a 12-6-6, 12-4-8 or 16- 4-8 at the rate of 1 to 2 pounds per 100 ft² and repeat every six weeks. You can also use one of the Espoma organic fertilizers at a rate of 4-7 pounds per 100 ft².

Plant Problems:
With warm temperatures and high humidity come lots of pests and diseases of plants. If you use an overhead irrigation system, make sure it runs during the early morning hours. If you hand water be sure to direct the water towards the ground or the soil in potted plants and not the foliage. Be careful not to overwater as plant roots may rot and dieback of branches and stems may occur. Keep a look out for the start of fungal leaf spots in lawns and on the foliage of ornamental plants as well as fruit and vegetable plants. Plant problems that have been brought to the nursery recently have included muhly grass mealybugs, green stinkbugs on tomatoes, dieback on gardenia, citrus leafminer, cercospora leaf spot of citrus, and anthracnose on Sunshine ligustrum. Correct identification of a pest is critical to determining how to manage it.

Your perceived pest may actually be a gardener’s friend. There are many beneficial insects and other arthropods that can help reduce pest populations so encourage them to take up residence in your yard.

To learn more about the ‘good” bugs please visit:
https://hgic.clemson.edu/factsheet/incorporating-beneficials-into-the-gardeners-toolkit/

We’ve also seen nutrient deficiency problems such as interveinal chlorosis due to a magnesium deficiency or too low of a soil pH. So be sure to have your soil tested. Correct any pH issues so your plants will be able to get maximum benefit from the fertilizers that you apply.

For directions on taking a soil sample please visit:
https://hgic.clemson.edu/factsheet/soil-testing/