Karen Cambre, Sharpe, Kenneth W.
With a warmer winter last year we had a longer growing season. The result can be more growth on plants than expected. Late August is a second chance to remove excessive growth on roses during this year.
For a number of years roses were just too hard to grow and only the most dedicated gardeners would make the attempt. There were so many problems with diseases, especially black spot, in our hot humid environment that the use of roses in the landscape was limited.
With the introduction of shrub roses we have seen the use of roses explode. Shrub roses, also called landscape roses, are different than the traditional hybrid tea roses. Hybrid tea roses produce a large flower on the end of a long stem and are used as cut flowers. Shrub roses, as the name implies, grow more in a shrub fashion and the flowers are produced in clusters and those blooms are smaller. The real advantage is that shrub roses have lower maintenance and many of them have resistance to black spot and powdery mildew. This allows the novice growers to produce acceptable roses that require less spraying and care.
You probably know shrub roses by their trade names such as Knockout, Home Run, Carefree Celebration, etc.
When these rose varieties were released their tags would indicate how large the average plant would grow. Obviously they did not evaluate them just for south Louisiana so plants here get larger. Knock Out roses are very popular and are planted in home and commercial planting everywhere I look. They are typical of plants outgrowing their intended space. They are reported to grow 4-5’ tall x 4-5’ wide. I have seen Knock Out roses locally that were larger than 8 feet wide by 8 feet tall.
Fortunately, you have an opportunity in late August to early September to go in and use selective pruning to get size reduction and increase fall flower production. For all shrub roses you can take out as much as one-third of total growth now, if necessary, to reduce plant size. If you need to reduce the size further, wait for January and then you can cut shrub roses back by up to two-thirds.
Hybrid-tea roses and other large rose varieties can benefit from pruning now also. Your reward will be an increase in fall blooming. Pruning should be accomplished by cutting canes back to within about 30 inches of the soil. Also remove any deadwood now.
Climbing roses are handled differently because they have a different blooming cycle. The old style climbing roses, such as Seven Sisters, should only be pruned right after blooming. They usually bloom around Mother’s Day. Pruning climbing roses now would remove all of the flower buds for next year’s production. If climbing roses are growing outside of their intended space wait for them to finish blooming next summer and then prune.
When you finish pruning roses be sure to remove all weeds and add organic mulch now if needed. You should also apply a light application of fertilizer to give them a push for more flower production, but you have to be careful not to push too hard. Winter will be here before you know it and the roses will need to slow back down and harden off to prevent cold damage.