Mulch for Weed Control

Landscaping with mulch around the house often involves a number of considerations.  One of the most important is weed control and not having to spend a lot of time keeping up with it. One of the most unsightly things around the house can be a mowed lawn surrounded by weeds. A well-prepared and installed stone or bark mulch application can keep the need for weed control to a minimum. It can also make mowing easier around trees and plantings.

Bedding Preperation Prior To Planting

New bedding areas should be prepared prior to mulching. It is not a good idea to count on the mulch to kill and control what is already present.  It is best to eliminate any current vegetation where you are going to be creating a decorative and effective mulch bed.  By fully eliminating all growth you will prevent work and maintenance in your landscaping for some time to come. Most times, a project comes up and you want to get it done.  Tilling or hoeing the area to mechanically remove all growth is the usual means. If there is time to plan ahead and wait for a weed killer to work, it would save the effort to mechanically clean out all vegetation. Based on the time frame available, make sure you do one of the above steps to get all established growth out of the area.

Mulching controls weeds from getting started in the landscaping by depriving the weeds what they need to grow. They need nutrition, a suitable growing medium, water and sunlight to prosper. Of these three key survival needs, the easiest one to control is the sunlight. Applying the mulch deep enough is the first way to prevent weed growth. In addition to this some people install a weed prevention fabric before the mulch.  With an ever-increasing interest in recycling, a great use of newspaper is to put it down five to 10 sheets thick as an added barrier to sunlight germinating the seed. This will break down over time and help the organic soil content. Check our Mulch Calculator to see how much mulch you may need.  If you use a large chunk type of bark mulch, you should go deeper so you do not lose the effect of blocking sunlight to the soil.

Black Plastic

Using black plastic under mulch to create a weed control barrier can be very effective but has some other things to consider. If the ground is sloped, the mulch may wash off with a heavy storm. The plastic will not normally degrade, so if something changes it will have to be removed. 

Pre-emergent Weed Killer

Depending on your feelings on weed killers, an additional step can be to apply a pre-emergent weed killer that acts on the young seedlings as soon as they sprout. Weed killers distort the plant's ability to grow and its metabolic process.

Application of the Mulch

When the area to be mulched is ready, apply the mulch as soon as possible. Leaving the landscaping tilled and exposed to the sun provides the available seeds a chance to germinate.  Tests have shown that 4” of wood mulch is very effective in controlling weeds over time. Do it right and you will be able to enjoy a decorative area of your landscaping that will remain weed free for some time to come.

One key point to maintenance of the landscaping area is mulch can be added over time as the lowest part of the chips tends to degrade. Additionally, adding a pre-emergent weed killer can supplement the weed controlling effect of the mulch.  If you are more inclined to staying all organic, just keep up with replacing the mulch as needed and an occasional spot weeding of the mulched beds.

An environmentally-safe way to maintain mulched beds is to use vinegar on new growth if it starts to get established. Young growth weeds are more susceptible to weed control than established, well-rooted plants. Vinegar, with a high acid content, can be effective.  Click here for more information.

Enjoy a weed-free year with a properly-installed and mulched planting area. A little more effort up front can result in a nice looking, mulched, manicured property that is pleasing to the eye and the environment.