Weekly Express-News Article

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist
Saturday, August 9, 2008

“Preparing Roses for the Fall Bloom Period”

            It is hard to believe that it will ever cool down again, but it will and when it does this fall the roses will put on a flush of foliage and bloom again until the really cold weather arrives.

 

            To prepare for the fall bloom requires that you take some action now.  Be prudent about your gardening activities – do the most demanding work in the morning when it is relatively cool.  Wear loose fitting clothes, but despite the heat when you are working with roses, it is advisable that you wear long sleeves, gloves, and long pants.  Most rose varieties have serious thorns. 

 

            Begin your autumn preparations by pulling off any vines and cutting any hackberries (or other weeds) that have invaded the rose bed.  It takes some time, but it is worth it for long-term control to apply Vine and Stump Killer to the cut.  Greenbriar, mulberry, hackberries, four o’clocks, queen’s crown, and other weeds that may have taken root in your rose bed will vigorously re-sprout.  Put a drop of the V+S Killer on the fresh cut, and the weeds will usually be killed, including the roots. The product has an application like that found on a glue bottle and uses the same active ingredient that is used to kill hackberries or fence lines. 

 

            Next, prune out all the dead and diseased wood.  The roses can be opened up by removing stems growing towards the center of the plant.  Wayward branches such as those that grow across paths or straight into the air can also be removed, but the pruning should not eliminate as much wood as you do in the spring. 

 

            Compliment the pruning by restoring your spray program, irrigation, and fertilization.  Hybrid tea roses should be watered every week.  The old-fashioned and modern roses bred for toughness may not need as much water, but even the toughest antique rose blooms better with an irrigation application every two to three weeks.  It is best if the water is applied by drip irrigation or a hand hose.  Most modern roses are prone to develop foliage diseases if water is applied by rain or sprinkler to the foliage.

 

            A spray program is designed to prevent or reduce the damage done by insect and diseases.  Thrips and beetles are the usual insect culprits.  They have traditionally been controlled by acephate (Orthene).  It is effective because of its potency and its systemic nature.  I understand that the Bayer 2 in 1 product is also now used by some rose gardeners.  Organic gardeners can try a combination of Rose Defense (neem oil), Pyrethrum, and Spinosad.

 

            Thrips are tiny transparent elongated insects that attack flower and leaf buds with their rasping mouth parts.  The result is disfigured blooms and leaves.  Flowers are deformed with brown petal edges and quite often maroon streaking on the petals. 

 

            The beetles are Japanese beetle type insects that feed on the flower petals. 

 

            For disease prevention, organic gardeners use sulfur products and Rose Defense.  Individuals who use manufactured products generally utilize Funginex.  The target disease is black spot.

 

            Black spot produces a symptom of black spots surrounded by yellow halos on the foliage.  Quite often the spots run together and the yellow covers most of the leaf.  In the case of severe infections the plant will defoliate, and of course there will be no blooms. 

 

            Roses are heavy feeders.  Slow release lawn fertilizer (18-5-9) work well at the rate of one cup for a small plant, and two cups for a large plant spread under the canopy and at the drip line.  There are also a large selection of fertilizers especially formulated for roses.  If you use them, follow the instructions provided on the container.

           

            Mulch is an essential part of rose culture.  The mulch keeps the shallow roots cool and moist plus reduces weed growth.  Oak leaves, pecan shells, shredded brush, and most organic mulches do the job admirably.  Place three to four inches of mulch over the root system of every rose.