August is a tough month for gardening. The heat, humidity, molds, mildews and bugs have all taken their toll on our outdoor plants. August is not generally thought of as a great time to garden in the Southeast. But there are some things to do now that can make a big difference in your landscape and garden in the near future.
Now’s a good time to cleanup your roses for fall flower production. Many gardeners neglect their roses during the busy summer months. We are having hot, humid weather and as a result, black spot and powdery mildew have been prevalent. As a result, you’ll need to have your roses on a regular spray schedule for these diseases. Do some pruning to remove diseased and dead shoots and prune back weak, leggy branches. Finally, if the roses have not been fertilized recently, an application of fertilizer is suggested. With some care, you’ll be surprised how well neglected rose plants respond and bloom during late summer and fall.
Many common woody ornamentals like oleander, hydrangeas and azaleas can be propagated by cuttings this time of year. For azaleas, take tip cuttings 3 to 5 inches long with several leaves left attached. Many rooting mediums can be used such as sand or a mixture of peat and perlite. Place the cuttings in the media and keep moist by covering with a plastic bag or use a mist system. A rooting hormone may hasten root growth. If you have any cold sensitive ornamentals, try rooting cuttings before winter and keep the young plants in a protected spot this winter. Then, if the ornamental freezes, you'll have replacements for the spring.
Late summer and early fall is an ideal time to lift daylily clumps, divide and replant them. Retain as many of the roots as possible with each division. Cut back the foliage to 1/3 its original height. Make sure to prepare the soil in the bed adequately by loosening it and amending it with organic matter such as compost or peat moss. A light application of fertilizer can be added at planting time. Daylilies should not be planted too deep. Set the new divisions as deep as they grew originally.
Now is a good time to force crape myrtles to flower again. Just remove (deadhead) the spent flowers or seedpods, pruning just the terminal seed cluster. This forces new growth and repeat flowering. It will probably take four to six weeks before you’ll be enjoying a second flush of blooms on your crape myrtle. This technique also works on chaste trees (Vitex).
Larry Williams, UF/IFAS Extension Agent, Okaloosa County, August 18, 2011