By Sharon Driskill, Somervell County Master Gardener
One of the most popular roses in North America is the Knock Out rose. The Knock Out rose bush was created by Bill Radler. It is one of the most popular roses in North America. They are easy to grow and do not require much care. They are also very disease resistant. Their bloom cycle is about every five to six weeks. These roses are known as “self-cleaning” roses, so there is no real need to deadhead them. They are heat tolerant so they do well in most sunny and hot locations. When it comes to growing Knock Out roses, they can pretty much be listed as plant them and forget them roses. If they do get a little out of the shape, a quick trimming here and there will suffice. If no pruning is done to adjust their height and/or width, the Knock Out roses can reach 3 to 4 feet wide and 3 to 4 feet tall. In some areas, an early spring pruning 12 to 18 inches above the ground works well, while in areas with harder winters they may be pruned down to around 3 inches above the ground to remove the dieback of the canes. A good early spring pruning is highly recommended to help get the top performance out of these rose bushes. When caring for Knock Out roses, feeding them a good organic or chemical granular rose food for their first spring feeding is recommended to get them off to a good start. Foliar feedings from then on until the last feeding of the season works just fine to keep them well fed, happy and blooming. Knock Out rose bushes were bred to be a low maintenance.
There is one disease that can harm your Knock Out rose. It is Rose Rosette Disease. Some research indicates that the carrier of this dreaded virus is the eriophyid mite, a very tiny wingless mite that is easily moved about by the wind. Where bushes are planted closely together, such as the case with landscape roses like Knock Outs, the disease seems to spread like wildfire. Once a rose bush contracts the nasty virus, it is said to have Rose Rosette Disease (RRD) forever, as there is no known cure for the disease. The infected rose bush should be removed and destroyed immediately. Any roots left in the soil will still be infected, thus no new roses are to be planted in the same area until there are no more roots in the soil. If any shoots come up in the area where diseased bushes have been removed, they need to be dug out and destroyed. The new growth on Rose Rosette Disease is often elongated with a bright red coloration. The new growth is bunched up at the end of the canes, an appearance that brought about the name Witches Broom. The leaves are typically smaller, as are the buds and blooms that are distorted. The thorns on the infected growth are typically more abundant and at the start of the new growth cycle, are softer than the normal thorns. Once infected, RRD seems to open up the door for other diseases. The combined attacks weaken the rose bush to the point that it will usually die within two to five years. The best way to avoid the disease is to inspect the bushes well when purchasing. The new growth on many rose bushes will be a deep red to maroon color. However, the new growth on an infected rosebush will look distorted/disfigured compared to the foliage on others. There are times when spraying an herbicide may have drifted over onto the rose foliage. The damage the herbicide does may look very much like Rose Rosette Disease but the telltale difference is the intense red stem color. Herbicide damage will usually leave the stem or upper cane green. Heavy pruning to remove the diseased portions does not work. It is recommended that the Knock Out rose bushes be planted so that their foliage is not packed tightly together. They will still bush out and provide a grand and colorful display of blooms. Don’t be afraid to prune Knock Outs back to keep some space between them if they do start to grow closer. It is far better for the overall health of the bushes to allow them some free air space. A Knock Out rose with RRD is pictured below.
Another benefit of growing Knock Out roses is the unending supply of rose petals which is needed if you like to make rose jelly. It is rewarding to have beautiful roses to enjoy but it is also nice to be able to share this special jelly with family and friends. The recipe below is one that I have tweaked over the years. I first tasted rose jelly years ago when I went to Norway. Our hostess served it with reindeer and what a treat it was. Any type of rose may be used but make sure to use only petals from rosebushes that have not been sprayed with chemicals. The more fragrant the rose, the more fragrant the jelly.
Rose Jelly Recipe
To 3 cups of rose water*, mix in 1 box pectin, stir until dissolved and bring to a hard boil. Add 3 cups sugar and bring mixture to another hard boil for 2 minutes. Pour into prepared jars. Makes five 8 oz. jars. You may also double the recipe. I like the color of mine to be natural but you can use food coloring if you choose. I also like to put a thin layer of wax in each jar while the jelly is still hot. This makes for a nice seal. To make a pretty presentation, I hot glue a silk rose on the lid after cooling and wrap a ribbon around the neck of the jar and finish with a pretty label.
*rose water-I use 10-12 cups of rose petals that have been gently washed. Place in saucepan with 3 cups water and bring to a boil. Turn off the heat, cover, and let steep for 30-40 minutes. Drain through a colander first, then through cheese cloth.