invasive rose bush in iris patch

Asked April 24, 2018, 12:55 PM EDT

Help, I have what i think is called a prairie rose bush that has become invasive and mixed in with my daffodils and irises. what can i do? the irises need to be dug anyway but can i dig them in the spring or only late summer? could i dip the rose bush stems in roundup? thanks

Mower County Minnesota

1 Response

Thank you for the question. Bearded iris are best divided after they finish blooming in late summer. This gives them enough time to establish before the soil freezes. If you have Siberian iris, these can be divided in the spring, just as they show signs of growth, or in the fall, like the bearded iris. Here is our publication on growing and caring for irises:

Some rose bush plants can become quite invasive and controlling their growth will take persistence and effort. If you have bearded irises, you will have to try to control the rose without hurting desired plants. You can apply Roundup to the rose growth this spring but be very careful. Roundup is a non-selective herbicide and it will kill all plants it comes into contact with. Always read the package directions and apply exactly as directed. The only recommendations on application strategies are those on the label of the product you purchase. Any other methods are off label and we can't support them. You can try to cover the irises with something to protect them from any contact while applying the herbicide.
If you have Siberian irises, you could dig them all up, set them aside so there is no chance of herbicide drift reaching them, and treat the entire bed with Roundup. Follow package directions for replanting the treated area. Of course, you can't do this if there are other desirable plants mixed in there.
Even if you do use an herbicide, you will still have to watch for rose bush shoots and dig them out promptly. It may take a few years before no more emerge.

Thank you for contacting Extension.