How to Win the War on Weeds in Your Landscape

Q. People in this house before us had grass in the front and in the back. Before selling the property, they put plastic sheeting over the grass and rocks on top of that. The plastic, I think, is just keeping everything moist underneath it and the grass and weeds just keep on coming up.

Weeds growing in a desert landscape.. Developing a good landscape design that minimizes the wet areas in a landscape will help to control weeds.

A. Putting plastic under rock mulch is never a good idea. Think of it this way: plastic is temporary. Rock is permanent. Never put something temporary under something permanent.

            Putting temporary plastic mulch under permanent rock mulch always results in plastic emerging through the rocks at some time. This is unsightly, weeds emerge through holes in the plastic and the plastic eventually emerges through the rock. This requires the owner to pull the plastic out from under the rocks to keep it from becoming unsightly.

This is a black plastic that was put under the rock in a rock landscape. Sooner or later the black plastic develops holes and begins to tear or rip. When this happens it begins to emerge from the rock and becomes very unsightly.

            A more effective and permanent mulch under the rock is made from landscape fabrics. These fabrics are either woven or spun with tiny holes in them for air and water and have a long durability. They last a lot longer than plastic.

Nutgrass which is sometimes called nutsedge,
a very tough weed to destroy when it gets in your landscape.

            They are expensive compared with plastic. And landscape fabrics do not prevent Bermudagrass or nutgrass from coming through it, a couple of very tough weeds to control.

            Instead, put down a thicker layer of rock, 3 to 4 inches deep and no smaller than ½ inch minus. Over time, dirt accumulates in rock mulch and weeds grow in it but at least they will be easier to pull or kill.

One of the better hoes I have used in rock mulch is the Hula hoe, sometimes called a stirrup hoe or simply  scuffle hoe.

            The secret to good weed control is killing weeds as soon as you see them. During the first year, this requires weekly visits to your landscape and removing them with a hoe, pulling, using a fire weeder or chemicals. If pulling them, water the area first and pull them 30 minutes later. They are much easier to pull.

            The first time controlling weeds, knock them all down by hand, fire or with chemicals and remove any weeds with flowers or seedpods from the property. In one to two weeks, weeds will come back with a vengeance. Control these infested areas as soon you see them. The third week, other areas will emerge with weeds. Control them immediately as well. Do this persistently and weekly for the next 2 to 3 months, pulling or killing them as soon as they appear.

More black plastic emerging from underneath rock applied to the surface as a mulch. Never put a temporary mulch like plastic under a permanent mulch such as rock.

            In the second year, most of the weeds will be controlled. Just control the “hotspots”. By the third season, hotspots will appear occasionally and then control is needed only as weeds become problems. Yes, this sounds like a lot of work but most will be under control in 2 to 3 months and the work becomes easier.

            The mistake people make is diligence, staying on top of it. Once weeds become established, you lose the “war against weeds”.