by Bethany Hayes
Raised garden beds are slowly growing in popularity; it has several advantages over in-ground gardening. One of the most common questions about raised bed gardening is what you need to put at the bottom of a raised garden bed.
Putting a barrier at the bottom of a raised garden bed prevents weeds from coming up; everyone knows that the fewer weeds in the garden, the better it is.
Gardeners have several options for raised garden bed barriers. You might use newspaper, cardboard, leaves, or nothing at all. Something to remember is that each barrier option has pros and cons to consider before using it.
Let’s dive into lining a raised garden bed and what you need to know.
Do You Need to Put Anything at the Bottom of a Raised Garden Bed?
Adding materials or a barrier at the bottom of a raised garden bed is not a requirement. Many gardeners never use any barrier as long as the beds are over grass.
If your garden bed is less than six inches deep, you shouldn’t use a barrier because having a barrier in a shallow bed might stop the growth of the plants’ roots.
Leaving nothing at the bottom of the garden bed is no big deal, but since the weeds won’t be suppressed, you’ll need to use some sort of mulch at the top of your garden to stop weeds from growing. Weeds aren’t only unsightly; they compete with your plants for vital nutrients. You want your plants to get all the nutrients, not the weeds!
9 Things to Put at the Bottom of a Raised Garden Bed
Newspaper is one of the cheapest things to put at the bottom of a raised garden bed. The daily newspaper costs less than $2, and if you ask your friends and family, chances are they’ll give you their used newspapers.
Using newspapers on the bottom of a raised garden bed is so easy. All you have to do is spread the sheets across the bottom of the bed and fill the garden bed with soil.
Newspapers decompose slower than most people assume, but given time, they will decompose well. Once decomposed, newspaper releases carbon into your soil, a nutrient needed by plants. Carbon feeds microbes that live in the ground.
Remember, the thicker the layers, the slower newspaper decomposes. So, if you want to avoid decomposition, put more layers of newspaper on top of each other!
Cardboard is another popular raised garden bed barrier material. It’s cheap and abundant like newspapers. In most cases, if you ask friends and family, you’ll be able to source the cardboard for cheap or nearly free.
Cardboard has some pros and cons. It’s thicker, so it decomposes over time, but it takes quite a bit of time for that to happen. Cardboard takes four to six months at minimum to decay, but some types of cardboard will decompose slower.
Make sure you avoid any cardboard that has glossy print on it, so that includes cereal boxes, soda boxes, and shoe boxes. That type of ink is different from the soy ink used for newspapers; the glossy ink releases chemicals and toxins that you don’t want near your plants.
- Landscape Fabric
Landscape fabric is an investment, but some fabric is truly worth it. Some brands last for over ten years, so if you plan to garden quite a bit for years, this could be worth considering.
The biggest advantage to using landscape fabric is that it’s durable and resistant to decomposition. Some people line the top of their garden beds with landscaping fabric instead of the bottom. If that’s something you would like to try, all you have to do is cut or burn holes into the material to plant your seedlings.
Despite being fabric, it is permeable, so water goes through it. Also, it blocks out sunlight, so it suppresses weeds.
Overall, landscape fabric is a great choice, but it costs money. So, if you have a large garden, you might not be able to afford the cost. Also, make sure you don’t confuse landscaping fabric and landscaping plastic; it’s not the same!
Another excellent alternative to landscape fabric is burlap. It doesn’t last as long as landscaping fabric, but it takes years to decompose. It lets water pass through, suppresses weeds, and is eco-friendly. Burlap is made from the fibers of jute plants, so you don’t have to worry about it harming your plants.
It comes from a plant!
The only disadvantage of using burlap is that it frays easily, and cutting it to the right size you need could feel frustrating.
Consider using leaves from your backyard if you want something free to use at the bottom of raised garden beds. Filling up a raised bed with leaves at the bottom of your garden bed is pretty easy, and leaves take six to 12 months to decompose fully, but they will decompose.
The more leaves you put at the bottom of your raised garden bed, the longer it takes to decompose! When leaves decompose, they’ll add nutrients to the soil, like carbon. So not only will leaves suppress weeds, but you’ll end up with healthier, nutrient-dense soil.
- Hardware Fabric
Hardware fabric is an excellent solution if you’re struggling with rodents or animals in your garden beds. It’s not used to get rid of weeds; all the holes make it impossible to suppress weeds, but it helps prevent the destruction of your plants.
If you aren’t worried about weeds but want to stop burrowing animals, hardware fabric is great. It won’t decompose, and it will last for years. So, despite being a bit pricey, it will last for several years once it’s laid.
You also can use hardware fabric in conjunction with any of the other barrier materials!
Most would never think to line the bottom of their garden beds with stone, but stones, rocks, and pebbles are a great option. It’s unique because rocks won’t decompose, so they become a permanent barrier.
Of course, using stones and rocks has its advantages. Unfortunately, it’s going to take a lot of stones to cover the bottom of your raised beds, so you might have to buy rocks. That gets pricey quickly.
Even if you’re able to fill most of the bottom of the bed with stones, chances are there will be gaps large enough for weeds to grow around. You could try to fix this by putting smaller stones around bigger stones to close gaps.
However, the biggest drawback is that it has poor drainage. Water cannot pass through rocks, so it has nowhere to go. That can lead to soggy soil and standing water, along with other problems. The only way to fix that is to leave the gaps between the stones, but the weeds grow up.
It’s easy to forget that wood is possible at the bottom of a raised bed garden. You can use logs, wooden planks, tree branches, wood scraps, or whatever else you want to use.
Wood is way more durable than other materials, taking years to decompose, but it does decompose. Of course, that does depend on the kind of wood you use, but untreated wood will rot within a few years.
You’ll need to make sure you add drainage holes to the wood if you’re using thick planks that might prevent water from escaping. It’s also to make sure that you never use pressure-treated wood because it contains potentially dangerous chemicals to plants.
Of course, it’s not required to put anything on the bottom of a raised garden bed, so you can leave the grass there. This won’t help keep weeds away, but it requires no setup or hassle at all.
You don’t have to put anything at the bottom of a raised garden bed, but if you want to suppress weeds, you have several materials to try. From newspapers to stones, something will work well for your budget and garden.
Belinda R. Voelschow Massingill says
Thank you for the information. It confirmed that I was on the right track. My only question is, if using old wood from trees we have cut down, is there a wood we should avoid, other than walnut? Thank you for sharing your knowledge!!! -BVM