When planning your home garden you may have heard whisperings of the necessity of garden bed liners. While it might feel like a hassle to line your garden bed, most experienced gardeners and landscapers recommend it on the basis that it might save you a lot of garden maintenance in the future. In this article, we will detail the benefits of garden bed liners, the different types of materials, and some extra gardening tips so that you can decide whether or not to place a liner in your garden bed and hopefully help you decide what you should line your raised garden bed with.
Do I need a liner for my garden bed?
While placing liners to cover the bottom of your raised garden bed is not essential, they can keep your soil healthier, protect plants, and prevent unwanted weed sprouts. Here are some of the biggest benefits of using a liner,(that is breathable and eco-friendly) in your home garden bed.
Insulation
Laying down a liner in your garden bed helps regulate any temperature fluctuations. Dramatic changes in temperature are harmful to plants, especially in cooler spring or fall months when temperatures begin to dip more frequently. However, liners, especially fabric liners, act as insulation for the soil which can protect plants from rapid changes in soil temperature.
Weed prevention
The majority of gardening labor is pulling out weeds, but with a liner, you can prevent weeds from growing up from the bottom. Suppressing unwanted weeds and grasses from popping up will help save you time in maintaining your garden.
Pest control
Certain heavy-duty liners, like hardware cloth, can drive away underground rodents like gophers and moles who burrow their way into your garden and harm plants.
What is the best liner for raised beds?
Now that you’ve skimmed the benefits to placing a liner in your elevated garden oasis, you need the basics of different liner materials. The best materials are ones that allow for water drainage and for worms and insects to get through. Here is a list of the best options for raised garden bed liners and their pros and cons:
Fabric
Pros
- Fabrics such as canvas, burlap or landscape fabric are breathable enough for proper airflow, water drainage and nutrient exchange.
- Most fabrics are a fairly affordable option, depending on where you source them.
- Fabrics, especially heavier duty ones, prevent weeds from growing by denying them enough sunlight.
Cons
- Depending on which fabric you choose, it might not be durable enough to prevent gophers and moles from chewing their way through.
- Will likely need to be replaced often as the fabrics will deteriorate over time.
Cardboard or newspaper
Pros
- Cardboard and newspapers are likely the cheapest and most plentiful options for a garden bed liner.
- Made from paper fibers obtained from wood pulp, both types of materials are natural and sustainable.
- If your garden bed is shallower, with say around three to four inches of soil, these materials will effectively prevent weed growth.
Cons
- Since these materials are biodegradable and will naturally decompose, they are a short-term solution that will not last over time.
- The higher your raised bed, the less effective cardboard or newspaper will be to suppress weeds. A bed with soil more than four inches deep will not benefit from a cardboard liner, since tough weeds that grow deep underground can easily grow through paper-based liners.
Metal hardware cloth or wire mesh
Pros
- Metal hardware cloths are guaranteed to keep out pests like gophers and moles, which can mosey their way through other materials like fabric and cardboard.
- Options with adequate space between the wires allow for water drainage while also retaining the soil.
- Rolls of metal, usually found at your local hardware store, are easy to find and are another affordable option.
Cons
- Certain hardware cloths are treated with chemicals that can leach into soil. Since they are placed under soil, metals can also rust and can also leach into soil. For a durable and nontoxic option, consider a metal liner that is made from untreated stainless steel.
- Wire mesh with larger holes, like chicken wire, can sometimes prove ineffective for keeping out smaller pests like chipmunks or moles, since these small creatures can make their way through the holes.
Metal hardware cloth or wire mesh
Pros
- If your garden bed is made from pressure-treated wood or your plants are exposed to toxic materials, plastic can prevent toxic chemicals from leaching into the soil and your plants.
Cons
- Non-porous plastic is typically not recommended by the gardening community because it can retain too much water, preventing proper water drainage and rotting your plants roots. If using a plastic liner, take the time to poke some holes to allow for proper water drainage.
- Plastics can keep out beneficial insects and worms that boost the health of your soil.
- If lining a wooden garden bed with plastic, it can accelerate the rotting process of the wood since the water won’t evaporate as fast and the moisture can get trapped between the wood and the plastic.
- As the plastic material degrades microplastics may leach into your soil and eventually be absorbed by your plants. To learn more about micro-plastic in your garden consult our plastic free gardening blog post .
What do I put on the bottom of a raised garden bed?
Considering the benefits and drawbacks to each liner material mentioned above, generally fabric and metal hardware cloth work best for suppressing weeds while still allowing for proper water drainage. Newspaper or cardboard will decompose quickly, and plastic retains too much water and can leech micro-plastics into your soil. However, each garden has its own unique circumstances so only you will be able to make the best decision based on your gardening needs.
Can I lay down multiple liners in my garden bed?
You can combine liners to address concerns specific to your garden bed conditions. For example, if you want to suppress weeds and pests, you can line down hardware cloth and then place cardboard over the top.
What do I put on the bottom of a raised garden bed on concrete?
If your garden bed is placed over concrete, say on your driveway, you’ll want to make sure to line your bed so that the soil doesn’t get washed away on the hard surface. Landscape fabric is usually the best option for this scenario, as this type of liner will hold the soil and place, but still allow for drainage.
How to garden with a raised bed over contaminated soil?
If your city or county has informed you that your area has contaminated soil, such as with toxic metals or PFAS, you’ll want to place a heavy-duty liner to prevent the roots of your plants from reaching the native soil and absorbing these chemicals. For more information about urban gardening and how to determine if your property is contaminated, consult this guide from the Environmental Protection Agency.
So, What Should I Line My Raised Garden Bed With?
Having considered this overview on garden bed liners, you should now be able to make a decision on if your garden bed could benefit from a liner, and which type is most suitable to your gardening conditions. In most cases, a good quality landscape fabric is a versatile and effective choice. If you’re concerned about burrowing pests, adding a layer of hardware cloth to the bottom is highly recommended.