Roses need attention during summer

John Young, Gill, Daniel J., Owings, Allen D.  |  7/15/2009 6:16:06 PM

Sustainable Landscape News From LaHouse Distributed 07/15/09

By LSU AgCenter Horticulturists Dan Gill, Allen Owings and John Young

Summer is not the most enjoyable time to work in the yard in Louisiana, but rose bushes need attention to ensure good performance through the summer and into the early fall months.

The popular landscape shrub roses, such as the Knock Out variety, are found by the hundreds now across Louisiana. Traditional hybrid tea, grandiflora and floribunda types remain popular, too.

During the summer, you may notice the flower colors are less intense and the blooms are smaller. These conditions are simply the effects of the summer heat. Improved flower color and flower size will occur this fall.

Roses need disease management and proper fertilization from July through the end of summer for good flowering and performance into the fall. Irrigation also needs to be maintained during drought-like periods.

Do not prune roses in June and July other than taking off old flowers as they fade. “Dead-heading” in these months means less pruning later. We recommend late summer pruning of modern rose varieties such as hybrid tea, floribunda, grandiflora and shrub roses. Complete the pruning by early September in south Louisiana. Blooms will return on the pruned bushes 40 to 45 days later.

Here are tips on other rose garden care we recommend in summer:

– Watch roses for insect pests. Spider mites, aphids, thrips and cucumber beetles usually are the main problem insects on roses. Some insects can be easily controlled; some are more difficult to control. Monitor your plants weekly for insect infestations.

– Clear debris from rose beds and pull any weeds that may be present. Add Preen or Amaze pre-emergence herbicide for summer weed control.

– Add new mulch if you did not refresh the bed earlier in the year (pine straw is an excellent material). Even if you did add mulch earlier in the season, a new application on top of the older mulch may be beneficial. Three inches of pine straw is ideal.

– Continue a preventive fungicide spray program for blackspot control. Treatment depends greatly on what kind of roses you have, because roses have varying degrees of blackspot susceptibility. Spray on a 10-14 day schedule on susceptible varieties.

– Spread a light application of a slow-release fertilizer now, especially if plants are not growing well. You also should fertilize lightly at the time of late summer pruning.

Come to LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is located near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge across the street from the LSU baseball stadium. Go online to Louisiana Yards and Neighborhoods for additional information.

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Editor: Mark Claesgens

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