Blue rug is the nickname for the groundcover, Juniperus horizontalis "Wiltonii." It takes the nickname for its ability to spread into a silvery blue, carpet over the landscape. Because the juniper isn't as dense as turf, weeds have an easy time getting a toehold and proliferating. Keeping weeds in check takes diligence and a good selective herbicide with the active ingredient, imazaquin. as the active ingredient. Blue rug juniper is hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9.
How it Works
The herbicide enters the weeds through the roots, the foliage or both, and moves throughout the plant. The weeds stop growing, and the newest leaves turn yellow. As they slowly die, the plants turn from yellow to brown and wilt. It may take several weeks for some weeds to die. Because this is a selective herbicide, it typically kills only select plants that are listed on the label. Imazaquin kills a broad range of weeds without harming the blue rug juniper. Effectiveness depends on how much moisture is in the soil both before and after applying the herbicide.
Weeds should be young and actively growing for the herbicide to be most effective. Avoid applying it on a day with winds in excess of 10 miles per hour or when the temperature exceeds 85 degrees Fahrenheit. Herbicide carried on the wind may end up harming desirable ornamental plants, while excessive heat interacting with the herbicide causes scorching of the juniper. Give the juniper bed 1/2 inch of water the day before applying the herbicide.
When broadcasting the application, the amount of herbicide to use depends on the size of the weed infestation. 2 ounces of imazaquin in 1 gallon of water is sufficient for a light infestation, while 2.6 ounces per gallon of water is required when there are many weeds. One gallon of the solution will treat a 1,000 square foot area. When you mix the solution, add the water and the herbicide to the sprayer tank. Then swirl the tank gently as you add 1 teaspoon of a non-ionic surfactant – available online and in large gardening centers – to the tank. Surfactants help the herbicide stick to and penetrate the weed's leaf surfaces.
Weeds in blue rug juniper can also be managed with spot treatments of imazaquin herbicides. This method is easiest when only a few weeds exist. Use a backpack or handheld sprayer filled with a solution of 3/4 teaspoon of herbicide and 1/2 teaspoon of surfactant in 1 gallon of water. Spray individual weeds until they are wet. No matter which method you choose, irrigate the area afterward with at least one-half inch of water to activate the herbicide.
Wear a long sleeved shirt, long pants, shoes and socks, a breathing mask and chemical resistant gloves when working with herbicides. If anything you wear becomes soaked with the product, discard it. Keep people and pets out of the area during the application and until the product dries. Always check the label to ensure you are using the right product for the plant you are treating, and follow all label instructions and precautions.