If you have raised garden beds, you may be wondering whether it is wise to line them, and if so, what you should use. I looked for pros and cons of lining raised beds, and I found both.
So, should you line a raised garden bed? Yes, you should line your raised garden bed, since the pros of doing so outweigh the cons. A liner for your raised garden bed can insulate the soil against extreme temperatures, keep moles and gophers out, and prevent weeds from growing. A raised bed liner will also allow water to drain away without taking soil with it.
Of course, there are some downsides to using raised bed liners, and we will discuss those as well. We’ll also look into the different materials you can use for raised bed liners, along with pros and cons of each.
If you want to buy quality raised garden beds to replace old ones or to start a new garden, then check out my picks for the best raised garden beds on Etsy.
Should You Line A Raised Garden Bed?
After weighing the pros and cons, I think that lining your raised garden bed is worthwhile. However, you may decide differently based on your own situation.
Let’s review the pros and cons of lining your raised garden bed, so that you can make an informed decision on your own.
Benefits Of Lining A Raised Garden Bed
Three of the main benefits of lining your raised garden bed are protection against temperatures, pests, and weeds. However, certain liners can also keep soil in your raised bed while allowing water to drain away. Finally, if you build your raised bed out of pressure treated wood or railroad ties, a liner can prevent harmful chemicals from leaching into the soil.
Raised Bed Liners Insulate Soil Against Extreme Temperatures
By their very nature, raised beds are sensitive to temperature fluctuations. The reason is that the soil in a raised bed is above ground and will gain or lose heat faster than soil in the ground. Using a liner in your raised bed can help to prevent these extreme temperature fluctuations.
A liner can help to hold heat from daytime sun in the soil. This will prevent damage to plant roots from nighttime cold or late spring frosts. Of course, you may also want to cover your plants with a cloche or row cover to protect the stems and leaves. For more information, check out my article on protecting plants from cold and frost.
Likewise, a liner can help to prevent the soil in your raised bed from heating up too quickly on a hot, sunny day. This will help to keep the soil from drying out so quickly in the summer.
Raised Bed Liners Keep Pests Out
Raised beds are great at keeping some pests away. However, a raised bed with no bottom may not do any good against moles, gophers, or other digging creatures.
If you line the bottom and sides of your raised bed properly, moles and gophers should not be able to dig their way through it. Even if they can dig through, it might not be worth the trouble, and so they will keep on digging for greener pastures.
A thin sheet of plastic is probably not enough to keep moles and gophers from digging through. You will want to use something a little tougher for your liner, such as hardware cloth (more on this later).
Raised Bed Liners Prevent Weeds From Growing
This is especially important if you have just installed a new raised bed, or are thinking of doing so. When you build a raised bed over a spot in your yard, there may be seeds from weeds in the soil under that spot.
Those seeds may eventually sprout and grow up into your raised bed. This is much more likely if your raised bed has no bottom.
You can prevent the problem of weeds with a liner, since most weeds will not be able to grow through plastic or cloth liners (at least when they are new!) Of course, seeds from weeds can still fall into your raised bed from wind, birds, or other animals. However, a liner does prevent one avenue for the growth of weeds in your raised bed.
Raised Bed Liners Retain Soil While Allowing Water To Drain Away
If your raised bed has no bottom, then it is possible that watering and rain can wash away soil. Over time, this will lead to a lack of organic material and nutrients for the plants in your raised bed.
Installing the proper liner for your raised bed will allow water to drain away without taking soil with it. Using liners made of cloth or other water-permeable materials means that your raised bed will drain properly without losing all of its nutrients over time.
Raised bed liners that allow proper drainage also prevent over watering. For more information, check out my article on over watering.
Raised Bed Liners Prevent Leaching Of Chemicals Into Soil
This won’t be a problem if you built your raised bed from untreated wood, brick, or stone. However, you may have used pressure-treated wood, railroad ties, or wood from pallets of a questionable origin.
In that case, the wood may contain chemicals that you do not want in your garden. If the wood is in direct contact with the soil, these chemicals can leach into the soil and eventually to your plants.
To prevent this, use a liner that will prevent this leaching, such as plastic. If you are also worried about water drainage, try using cloth or some other water-permeable material for the bottom of your raised bed, and plastic for the sides.
This will allow drainage through the bottom while preventing soil from contacting old wood that may contain chemicals.
Drawbacks Of Lining A Raised Garden Bed
For all their benefits, raised bed liners do have some drawbacks. First of all, a completely airtight and watertight liner material may not allow the drainage that your soil needs.
Also, it can be easy to damage some liners when digging or replacing soil in your raised bed. In addition, you will need to move all of the soil in your raised bed to replace an old liner. Finally, if your raised bed is built from wood, a liner can keep water in contact with the wood, causing it to rot faster.
Raised Bed Liners May Not Allow Adequate Drainage
If you use plastic that is not water-permeable, then water may have a difficult time draining out of your raised bed. This can keep the soil too moist, especially during periods of cool, wet weather.
Eventually, this can lead to root rot of the plants in your raised bed. If you are worried about this problem or live in an area that gets lots of rain, make sure to use a liner that is water-permeable.
Raised Bed Liners Are Easily Damaged By Digging
It is almost inevitable that you will need to dig in your raised garden bed. For example, you may need to harvest potatoes or other vegetables that grow underground. You may also need to dig up old plants to make room for new ones in the next growing season or year.
Either way, digging in your raised bed creates the risk of putting a hole in your liner. Some tougher liners will resist such damage, but thin plastic liners or old pool covers are pretty easy to cut with a trowel or shovel.
To avoid this, make sure you know how deep the liner is buried, and go easy as you dig deeper. Also, go easy when digging near the edges of the raised bed to avoid ripping the liner.
Raised Bed Liners Are Difficult To Replace
If you accidentally damage your raised bed liner, or it decays with age, then you will need to replace it. This is no easy task, since you will have to remove all of the dirt from the raised bed, take out the old liner, put in the new liner, and replace the dirt (either the old soil or new material).
Either way, you will need to move the entire volume of your raised bed not once, but twice, to replace your liner. This may create more work for you in some cases, but not if you plan well!
For example, let’s say that your raised bed is made of untreated wood, and you think it will last 5 years before rotting away. In that case, choose a material for your liner so that it lasts 5 years. That way, you can just remove the old raised bed and liner, and the build a new one, all at the same time.
Raised Bed Liners Can Cause Wood To Rot Faster
If you use untreated wood to build your raised bed, rotting due to water exposure is a big concern. Covering the wood with plastic on one side or both sides can trap moisture between the wood and plastic.
This can cause rapid rotting of the wood, especially in hot and humid climates. You can avoid this problem entirely with raised beds made from brick or stone, although the up-front cost will probably be much higher (unless you can score some free bricks from a friend who tore out an old chimney!)
What Do You Use To Line A Raised Garden Bed?
There are a few basic options when deciding what to use to line your raised bed. You can use some type of fabric, such landscape fabric or canvas (similar to a grow bag). You can also use some type of plastic, such as a tarp, pool cover, or polypropylene bed liner. You can even use a metal liner, such as hardware cloth.
Using Landscape Fabric As A Raised Bed Liner
Landscape fabric is normally used to prevent weeds by preventing them from getting sunlight. It is sometimes made from plastic or recycled materials, and is often sold in rolls at garden supply centers or online.
Landscape fabric is somewhat breathable and will allow water to permeate. If you use it to line your raised beds, it will allow the soil to drain while also preventing weeds from growing.
For more information, check out this article on landscape fabric from Wikipedia.
Using Canvas As A Raised Bed Liner
Canvas is a durable material made from cotton, linen, or hemp. It is often used for shoes, awnings, and tents. Canvas can also be used for gardening applications, such as grow bags or raised bed liners.
Canvas is a durable material, which makes it tougher and longer-lasting than most landscape fabrics. It is also somewhat water-permeable, meaning it will provide for decent drainage if you use it as a raised bed liner.
For more information, check out this article on canvas from Wikipedia.
Using Plastic As A Raised Bed Liner
You can use a tarp or an old pool cover as a raised bed liner, cutting to the necessary dimensions if it is too large.
However, many of these plastics are waterproof, meaning that they will not allow any drainage if used to line the bottom of your raised bed.
Your best bet is to use this type of plastic to line the sides of a raised bed made of older wood. This will prevent chemicals from leaching out of the wood and into the soil.
Another option is to order raised bed liners made of polypropylene fabric. These liners allow better drainage than other plastic sheet materials.
For more information, check out this article on polypropylene from Wikipedia.
Using Hardware Cloth As A Raised Bed Liner
Hardware cloth is a mesh material made of metal, often sold in rolls at hardware stores. You can use this strong material to line the bottom of your raised bed to prevent gophers and moles from digging in from below.
For more information on mesh materials, check out this article on mesh from Wikipedia.
Used together with canvas or landscape fabric, hardware cloth can help to prevent pests from digging into your garden while also allowing water to drain away without carrying soil with it.
Using Cardboard As A Raised Bed Liner
You can also opt to use cardboard as a raised bed liner. Just know that it will decompose quickly! For more information, check out my article on using cardboard boxes to grow plants.
By now, you have some ideas about why you should consider using a liner for your raised garden bed. You also know about the different materials you can use, along with some of the pitfalls and what to look out for.
I hope you found this article helpful – if so, please share it with someone who can use the information. If you have any questions on liners for a raised garden bed, please leave a comment below.