Many Utah roses have fallen victim to finicky fall weather. Late last November through early December, the weather in northern Utah went from 60-plus degrees to almost 0 in a matter of days. Unfortunately, this quick change brought about many black, dead rose plants. Consider this information.

 

• Most plants begin dropping their leaves and progress into dormancy about mid-to-late October. Roses, however, try to continue growing. Most years, this is not a problem, but when the temperature drops quickly from a comfortable growing temperature to well below freezing, the plants do not have enough time to acclimate. 

 

• Plants need a slow cooling process of about two to six weeks to prepare for winter. They drop their leaves and move water and energy out of the stems and into the roots. As the water leaves the cells in the stems, they harden and are ready for cold temperatures. That didn’t happen last fall. Basically, it was too much cold too fast, which caused many roses to die.

 

• When we get deep, freezing temperatures before the plant is ready, it compromises the integrity of the cells. This is similar to putting fresh strawberries in the freezer. They are healthy and firm going in, but the freezing action of expanding water (ice) punctures the cell walls, causing strawberries to become soft and soggy. In essence, the strawberries die, just like the roses did.

 

• At this point, it’s too late to do anything to help the roses. If approximately four to six inches of green remains at the base of the cane, the rose will eventually recover and should be fine. Remove all the blackened canes, but be aware that this may include removing the whole rose. If the cane is black all the way to the ground, the roots may still be alive, but the good part of the rose is dead. Some growth will occur, but it will not be the pretty rose that previously bloomed because the plant’s rootstock takes over. At this point, it’s best to just replace it. The good news is this will provide an opportunity to start fresh and plant new roses in the landscape.