Weed Control Fabric 101: How to Choose the Best Weed Barrier Material for your Landscape
Many homeowners and landscapers are plagued with weeds. Weeds in flower beds, in planter boxes, and throughout vegetable gardens. Much time and money are spent on herbicides, and manual weeding, so being able to use a weed barrier to thwart growth is an asset for those who don’t enjoy pulling weeds. A properly selected barrier can greatly reduce the amount of weed growth in the landscape and the required work to maintain planting areas. Weed barriers are not all created equal, and the overall effectiveness of the barrier will depend greatly on the grade of material purchased and whether it was installed correctly.
A weed barrier is a layer of geotextile fabric, plastic, or cardboard that is placed under soil and mulch to help block weed seeds from getting the light they need to germinate and grow through the soil. Weed barriers make weeding duties less difficult in vegetable gardens and flower beds.
(Heavy Duty Landscape Weed Control Fabric installed under mulch in flower beds)
Using a weed barrier can make the difference between having to battle weeds each spring and getting to launch straight into planting. Keep reading to learn more about weed barriers, how they work, and the best type to use in your landscaping.
A weed barrier is a type of material that is placed along edging, flower beds, vegetable gardens, and under rock installations to help prevent grass and other weeds from growing up around plantings.
Why Use a Weed Blocking Fabric (Weed Barrier)?
Weed block fabrics are rarely the only anti-weed strategy used in a garden, but they are incredibly helpful in reducing the number of perennial and annual weeds that return each spring in flower and vegetable beds before gardeners have a chance to plant seedlings there themselves.
• Landscaping professionals use weed barrier between plantings to keep their landscaping projects looking fresh and tidy for months after installing flower beds without the need for intensive daily or weekly weeding sessions.
• Home gardeners can also take advantage of weed barriers to make their gardening jobs less strenuous each season. Without a weed barrier, gardeners have to deal with many more weeds in their planting areas each spring than they would if an effective weed barrier was installed previously.
Weed Barrier Does More than Just Control Weeds
Without weed control, a gardener may be forced to till the soil to break the weeds up. This drives more weed seeds into the soil, and it is also disruptive to the structure of the soil. Using weed control fabric can prevent this vicious cycle altogether.
How Does a Weed Barrier Work?
A weed barrier works by adding a protective layer between the soil and a flower bed or planting area to prevent weed seeds from being able to germinate and grow up through the surface of the ground. Weeds need access to light, and without it, they can’t grow.
Commercial weed barriers are designed with the following elements in mind:
• UV resistance: Commercial weed barriers are typically designed with a built-in UV-inhibitor which helps the fabric resist decay when subjected to sunlight. UV resistant does not mean UV-proof. If the weed barrier is intended to last more than a season, it is typically recommended that the barrier is covered with either rock or soil to help to shield it from the sun.
• Permeability: Commercial weed barriers are usually designed to allow for water to drain through the material. This helps to prevent puddling in the landscape while allowing nutrients to reach the root zones of plantings.
• Tough material: Because commercial weed barriers are designed to last, this means the material is tough and durable. The actual level of durability will depend on the thickness or weight of the fabric. The heavier the fabric the more effective the weed protection.
DIY Weed Barriers
Along with commercial weed barriers, homemade weed barriers can also be used. These are usually constructed out of secondhand cardboard, newspaper, or newsprint. These homemade weed barriers are more biodegradable and easier to move around each year than commercial weed barriers. DIY weed barriers such as cardboard are good as they are biodegradable and environment friendly, however, they become much less effective in humid areas where they degrade very fast and typically only last a few months at most before needing to be replaced. (This can vary depending on soil conditions and precipitation)
(Cardboard boxes are broken down and used in a planter garden)
PRO TIP: If you live in a humid area or are looking for a longer-lasting weed control solution, selecting a heavy-duty commercial landscape barrier will be a better long-term solution for controlling weeds.
There are several different kinds of weed barriers available that gardeners and landscapers can use. Some of these types of barriers are meant to be laid down once at the beginning of a flower bed or landscaping installation, while others are meant to be put down each season to help prevent weeds from growing over the winter.
Here are some of the typical weed barriers that you are likely to run into:
• Landscape fabric: Landscape fabric is the commercial weed barrier that is used most often for weed suppression in landscaping projects, especially in barriers and beds where there isn’t a lot of maintenance activity anticipated (such as edges that contain perennial shrubs). Commercial-grade landscape fabric is tough and will last many seasons before needing to be replaced.
• Root Barrier: If you are trying to contain vary large varieties of weeds with thick roots a panel-style root barrier or a continuous barrier made of HDPE may be better suited to your application.
• Cardboard weed barrier: A cardboard weed barrier is a good option for a cheap and homemade alternative to commercial weed barriers. These barriers are formed by breaking down cardboard boxes into panels and laying these cardboard panels across flower beds and planting areas before applying mulch.
Both landscape fabric and cardboard weed barriers are good options for blocking weeds, and they can even be used together—landscape fabric can be used as the bulk of the protection, while cardboard can be laid down on the top of beds each year to provide a second layer to help keep weeds out during the off-season. Please keep in mind that the carboard weed barrier will rapidly break down and although effective at first will most likely become ineffective after a few months. Carboard should be seen as a temporary solution.
• Cardboard weed barriers are a better option for vegetable gardens where crop rotation necessitates that the plants in the plot be moved around regularly to combat plant pathogens in the soil. Many larger vegetable plants also have deep roots that you would have to cut a landscaping fabric to allow for.
• Landscape fabric is favorited for edge beds, flower beds, and around shrubbery. Because it’s meant to be left in place, it’s best in areas that don’t see a lot of action or require frequent maintenance during the growing season.
How to Put Down a Weed Control Fabric
Before starting a weed barrier installation, make sure that you have enough weed barrier for the entire planting. It’s a good idea to mark the weed barrier in each spot where you plan on planting a shrub or other plant through it. This will make it easier to figure out where the weed barrier needs to be cut.
Measure and Mark Your Weed Barrier Material
Measure the weed barrier to make sure that it fits the bed with about six inches of excess all the way around. Instead of cutting the edge, this part of the weed barrier will be folded and tucked around the edges of the planting to add extra protection from weeds at the vulnerable edges of the bed.
To keep the weed barrier in place, the garden staples should be hammered down at the barrier’s edges.
If you know ahead of time how many plants you’re putting down, it can be much easier to mark and cut the openings for the plants in the landscaping fabric before you install it. This is also a good way to see exactly how many plants you need for each section of the bed or edging.
Advantages and Disadvantages of Weed Barriers
While weed barriers can be useful for suppressing weeds in a landscaping or perennial bed, there can be both benefits and drawbacks to using this kind of material in the garden.
The Pros
Here are some of the advantages of using a weed barrier:
• Weed barriers reduce the number of weeds that come through in a bed. This suppression is important when rich, fertile topsoils are used, as nature abhors a vacuum, and weeds will quickly move into any bare soil if mulch and other weed barriers aren’t used to keep them down.
• Weed barriers reduce the need for physical weed-pulling labor. That makes them a great option for people with limited mobility or people who don’t have the time to get out and weed the garden every other day.
• Weed barriers can prevent gardens and flower beds from being overrun by weeds every spring, which can greatly reduce the amount of work that goes into readying the garden for the growing season. When plants die back in the winter, this leaves the ground vulnerable to weeds.
The Cons
Weed barriers have several benefits, but they do have a couple drawbacks as well. Here are some of the downsides of weed barriers:
• Weed barriers block beneficial insects: While weed barriers can prevent damaging insects from reaching plant root systems, they can also prevent beneficial insects from receiving the food and shelter they need to stick around. Earthworms can’t get through landscaping fabric to breathe at the surface of the soil, which will deter them from properly aerating these beds.
• Weed barriers take time to install: Installing a weed barrier in your beds will add more time to the project. For some this can be frustrating as taking more time from the project to get it installed can slightly delay a project. In our experience the additional time in putting in a barrier is well worth the time it saves in pulling weed in the future.
These issues are a problem with all weed barriers, but the worst offenders are plastic weed barriers. These weed barriers allow almost no moisture or oxygen to pass between the surface of the soil and the soil underground, and this can impede plants’ growth. We do not recommend using pure plastic barriers because of these issues.
Do You Still Need Mulch if You Have a Weed Barrier?
Many gardeners may wonder if they still need to use mulch if they have a weed barrier. The answer is YES; you should still use a mulch even if you have a weed barrier put into place. This is because mulch has other functions other than to block weeds, such as the following:
• Temperature protection: Mulch isn’t used just to keep weeds out of the garden. Mulch is also used to help prevent plant root systems from becoming overheated during the hottest parts of the summer and from becoming chilled during cold spring nights.
• Moisture retention: Along with acting as temperature control, mulch helps to keep any moisture on the beds in the soil where it belongs, rather than letting it roll away over the surface of the ground or from being evaporated by the sun. Most mulches are designed to hold moisture at the base of plants to keep them in good condition.
• Erosion prevention: Mulch helps keep soil from being washed away during rain and watering but weed fabric can also act to help keep soil in place if it is placed on top of the soil rather than beneath a layer of it.
For best results, a layer of weed barrier should be placed on top of the soil between the soil and the mulch. This allows the weed barrier to be easily accessed by the gardener. Once placed over the weed barrier, mulch can help to keep it in place. Mulch is also used in this instance to hide the weed barrier so that it isn’t visible in the landscaping.
Where Can You Use Weed Barriers?
Weed barriers are best used in stationary landscaping beds or beds where the plants are not moved from season to season. Here are some good uses for weed barriers in the garden:
• Hedges and landscaping beds where shrubs are used
• Any bed where perennial plants are used that will not have to be disrupted from season to season by planting activities
• Around tree plantings
• Underneath decks and other hardscapes
• Underneath rocks and gravel areas
Weed barriers are typically not recommended for beds where annuals are used, either annual flowers or vegetables. (Source: Bob Vila) This is because planting annuals each year can be tedious to do through a weed barrier, and the number of holes necessary to poke through a weed barrier for a bed full of annuals will effectively render it useless against suppressing weeds.
Vegetable gardens also need for their plants to be rotated each year to prevent the build-up of soil pathogens, and this usually means that the planting layout has to be changed each season. For this reason, it isn’t practical to use a weed barrier in beds that are constantly being rearranged each year.
When Should You Put Down Weed Barriers?
Weed barriers can be effective for helping to set up your garden for the year, but certain times are best for installing your weed barriers. These are the best types for doing a weed barrier installation:
• In the spring: If you’re getting ready to put in new shrubs, border beds, or beds for perennials, be sure to put down your weed barriers after the soil has been tilled (either rototilled or hand-tilled) but before the mulch is installed.
• In the fall: Installing weed barriers can be a good chore while winterizing your garden, especially if you want to start some new beds or borders before the new growing season in the spring. Fall is also the best time to put down temporary weed barriers such as cardboard used on vegetable beds that you plan to remove in the spring when it’s time to plant.
During installation of weed control fabric after graded landscape
No matter which time of year you decide to put in a weed barrier, you’ll want to be sure you do it before the bed is established, if possible. Putting in a weed barrier can be tedious if you have to remove the entire layer of mulch from the border first before you get started laying it down.
Can You Put a Weed Barrier Over Weeds?
While it’s best to clear as many weeds out of a bed as possible before installing a weed barrier, it is possible to place a weed barrier directly over existing weeds. The weed barrier should be able to smother any existing weeds and kill them, especially if mulch is used on top of the barrier.
The downside of using a weed barrier directly over preexisting weeds is that these weeds can self-sow seeds in the soil that will attempt to germinate and push through the weed barrier in the next growing season.
Depending on how many holes you end up cutting in your weed barrier to allow for planting, this can cause the weed barrier to be broken.
Tips for Using Weed Barrier Over Existing Weeds
If you plan on using a weed barrier over existing weeds without trying to pull them, here are a few ideas for making sure that existing weeds aren’t resurrected in the coming spring:
• Use a pre-emergent weed spray on the bed before installing the weed barrier. This will help kill any existing weeds and their seeds before they have a chance to self-sow.
• Place the weed barrier down in a bed with no plants in it so that you don’t have to cut any holes in it until the next season. This will give the weed barrier a chance to completely smother any weeds in the soil before you cut into it during the next planting.
• If you are placing down the weed barrier while winterizing a plot, it can be a good idea to withhold mulch until after planting so you can see the weed barrier clearly to cut through it to get to the soil beneath. Keep in mind that planting this way will make the task much more tedious and will require you to cut larger holes in the weed barrier for seedlings.
Putting down a weed barrier directly over a bed full of weeds can be a good way to knock the weeds down quickly, but it’s still a good idea to pull as many of the weeds as possible out of the bed as you can before putting down the barrier. This will help the weed barrier do its job more efficiently.
How to Lay Weed Barrier Fabric Around Plants
There are two major ways to lay a weed barrier down around plants, and either way, the weed barrier should be placed before the plants themselves. Weed barriers can be placed around preexisting trees and shrubs, but it is much more difficult to achieve a solid barrier this way.
Instead, weed barriers should be laid down around plants in the following ways:
• Lay the weed barrier down over the soil of the bed before cutting holes in the weed barrier to place shrubs or saplings. It can often be difficult to dig deep enough for these plants once a weed barrier has been installed without having to cut large holes in it to fit the plant’s root system through and to dig a deep enough spot, so this is not the optimal method.
• Measure and mark out the weed barrier before it’s installed, cutting holes where each of the plants is going to go in the bed. In this method, plants are placed first before the weed barrier is gently pulled over the top of them. Installing weed barriers in this way is much more efficient, but it isn’t always possible if you’re trying to install new plants in a bed with an old weed barrier.
When installing a weed barrier, it’s a good idea to think ahead as much as possible and figure out how the bed will be laid out before you start marking and cutting the barrier. This kind of project in the garden is a project where the adage “measure twice and cut once” will come into play.
Taking notes on paper can help you figure out and measure the spacing on your planting before you start installing the plants, and this, in turn, can show you exactly where you’ll need to cut your landscaping fabric to let them through.
How to Install Weed Barrier Under Rocks
Along with being useful in shrub borders and other edged landscapes, weed barrier is also useful when it is installed under gravel driveways and other gravel paths. This is because grass can easily sprout up between the gravel and make the path look untidy in a hurry. Weed barriers help keep the path smooth and clean.
To install a weed barrier under rocks, the weed barrier should be cut and laid down along the path of the gravel before the gravel is installed.
Make sure to secure the weed barrier carefully with plenty of garden stakes so that it doesn’t become disrupted by the soil and start poking up through the gravel. Weed barriers are meant to make gardens look nicer, but they’re ugly when they show.
Tips for Using Weed Barriers
Weed barriers can be a useful addition to your landscaping, but they can take some getting used to in order to use them effectively. Here are a few tips on how to get more mileage out of your weed barriers:
• Make sure that the soil is well-aerated and amended before placing a weed barrier. This is because earthworms and other aerating biological agents will not be able to operate effectively under a weed barrier, so you’ll have to ensure the quality of the soil yourself before installing it. If you don’t, you could end up with compacted soil and other growing issues.
• Make sure to buy extra. Don’t be afraid to buy extra weed barrier and cut it down to size, rather than buying the smallest amount possible. The worst place for weeds to get up through a weed barrier other than around the base of plants is around the edges of the barrier where the landscaping bed meets the grass.
• Make sure to mulch heavily over weed barriers. You don’t want any part of your weed barrier to show through to the surface of the soil since this makes more like to allow sunlight to penetrate beneath it. It also makes the garden look unkempt. Instead, make sure to mulch at least four to six inches over weed barriers so that they aren’t visible unless you dig.
Weed barriers can be an effective way to keep your gardens looking tidy, but only if they’re used correctly. If you try to cut corners or choose a cheap landscaping fabric that doesn’t allow moisture and oxygen to permeate, they’ll just end up being a hassle and an extra chore in the garden.
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