Grassy weeds growing in ground covers can be killed with grass killer for landscapes. This herbicide kills grass without killing broadleaf plants. Spray the weeds directly with Grass-B-Gon. In about 2 weeks, they will begin to turn yellow and die. Wait 3 weeks so you can clearly see which weeds have been killed, then go over the ground cover again, spraying any weeds you missed the first time.
The best way to deal with annual weeds like chickweed or annual bluegrass is to keep their seeds from sprouting. Find out when your weed is going to germinate, and spread garden weed preventer on the groundcover a week before that date. Garden weed preventer kills seeds as they germinate, but does not harm already-growing plants. Follow the package directions closely to be sure to get all the weeds.
step 3: Kill Grassy Weeds
Perennial broadleaf weeds are the most difficult to kill because the groundcover is a perennial broadleaf plant also. Most perennial weeds have deep root systems, so cannot be successfully dug up; pieces of root left in the soil will sprout again. Kill them with Roundup, used with a shield. The shield can be a piece of cardboard you put between the weed and groundcover plants so you can spray the weed without wetting the ground cover.
In most ground covers, one weed or just a few weeds cause all the problems. Take a sample to a garden center. Ask an experienced nursery person to identify it for you and tell you whether it’s an annual or perennial weed. If it’s an annual weed, you need to know when the seeds sprout.
step 2: Stop Annual Weeds Before they Start
A very effective shield can be made from a piece of heavy paper, lightweight aluminum sheeting, or a flexible sheet of plastic cut into a disk about 3 feet in diameter. Cut a hole in the center large enough to insert a spray nozzle and cut a slit from the hole to an edge. Bend the disk into a cone. You can adjust the size of the cone by overlapping the slit edge. Make the cone the right size for each weed, set it over the weed, and spray Roundup through the hole in the top.
Mowing too low weakens turf by reducing the ability of a grass leaf to produce enough nutrients. It also lets light hit the soil surface, which helps crabgrass and goosegrass seeds sprout and grow. Check with your local extension service for the recommended range of mowing heights for your grass type. Then mow at the highest level—usually between 2 and 4 inches.
Yes, you can. Synthetic landscape fabrics provide a physical barrier to weeds yet allow air, water and nutrients through to plant roots. Spread the fabric over bare soil around trees and shrubs; overlap several inches of fabric at the seams. Anchor the material with U-shaped metal pins, then conceal it with 1 to 2 in. of mulch, such as stone or bark chips.
Controlling weeds is a fight you can’t win entirely because they always grow back. But you can keep weeds under control by depriving new ones of the conditions they need to take root in the first place. Let’s look at how to prevent weeds from growing.
Apply Preemergence Herbicides
You can get in-depth information on drip irrigation from the Irrigation and Green Industry Network in the “Where to Find It” section.
Check the label to determine if it is safe for use around the kinds of landscape plants you have and effective against the weeds normally present.
As with most types of prevention, discouraging weed seeds from sprouting requires some extra time now so you can save a lot of time later.
Water Grass Infrequently and Deeply
Spread Landscape fabric and cut it to fit around plants. Photo by Saxon Holt
This Preemergence herbicide, made from corn gluten, is nontoxic. You can safely use it near all of your vegetables as well as around ornamental plants. Photo by Saxon Holt