Perhaps you’re just getting into gardening, or maybe you’re an experienced botanist looking to better your planting techniques. Whatever the case may be, many people are realizing the benefits of raised garden beds. But, what exactly do you put at the bottom of a raised garden bed?
There are a few great materials to use on the bottom of your raised garden bed. The cheapest and easiest to find include cardboard, newspaper, and leaves. If you don’t mind spending a bit, wood and landscape fabric are excellent options.
Below, we’ll discuss everything you need to know about using various materials on the bottom of your raised garden bed. Keep reading to learn more!
Why Have a Raised Garden Bed?
A raised garden bed is essentially a store-bought or homemade planting bed, anywhere from a few inches to a couple of feet high, that’s placed on top of the existing soil. Instead of planting directly into the ground, you fill the bed with potting and topsoil to better control the growing conditions and prevent weeds in your plants.
It’s often best to use a raised garden bed if you have poor-quality soil in your yard or if you want to decrease the level of work required to grow large, healthy plants. Most raised garden beds are placed in an area that allows you to walk around them instead of in them. This keeps the soil loose and fluffy, giving air and water more space to move through it.
Raised garden beds can be made of nearly any material, but wood and sturdy plastic are the most common. Before you begin laying soil, however, you need to place some material at the bottom of the bed to separate it from the ground below.
What Should Go on the Bottom of a Raised Garden Bed?
Placing a barrier between your soil and the ground is essential to separate the two types of soil and ensure your plants grow as strong as possible. Doing so will also prevent weeds from growing up from the ground and into your garden bed, reducing the work you have to do to maintain your garden. There are several materials you can use for this, but the most popular include:
- Wood
- Leaves
- Cardboard
- Newspaper
- Landscape fabric
Now, let’s discuss the benefits and drawbacks of using each on the bottom of your raised garden bed.
Wood
You can use any type of wood to separate your planting soil from the ground, including planks, logs, and branches. Wood is a popular choice because it takes much longer to decompose than other materials like newspaper or cardboard. Depending on the type and amount of wood you use, it will effectively deter weeds and offer a strong barrier for at least a couple of years.
Leaves
Leaves are often a great choice for the bottom of your raised garden bed. They will last approximately six months to one year before decomposing, and as they decompose, they add a lot of healthy organic matter to your soil. This improves both quality and fertility.
A leaf barrier will keep weeds out of your raised garden bed until they begin to decompose. To prevent weeds and decomposition for as long as possible, add several layers of leaves before pouring your soil. The multiple layers will clump together, strengthening your barrier and slowing decomposition significantly.
Cardboard
Many gardening enthusiasts recommend cardboard as a raised garden bed barrier because it’s cheap and plentiful. Thick or multi-layered sheets of cardboard often work best, as the thicker material will resist weeds and decomposition better than thinner sheets.
Cardboard will eventually decompose, but the organic cellulose in the paper will help keep your soil healthy when it does. Just be careful not to use any cardboard with glossy print — these contain chemicals that can release toxins into your soil as it decomposes.
While cardboard will do a sufficient job of keeping weeds out of your planting bed on its own, mulching with straw before adding your soil can help even more while also keeping your soil moist.
Newspaper
Like cardboard, the newspaper is an excellent choice for anyone on a budget or looking for ways to recycle old material. A few sheets of newspaper will be effective at preventing weed growth, but adding 5-6 layers all across the bottom will delay decomposition for as long as possible. Also, similar to cardboard, adding a layer of wood or straw mulch on top can do even more to prevent weed growth.
As the newspaper decomposes, it releases carbon into your soil and breaks down the cellulose in the paper. Carbon feeds the microbes in your soil, while cellulose will increase its fertility.
Landscape Fabric
If you don’t mind spending a bit of money on this project, landscape fabric is one of the most durable materials to put on the bottom of your garden bed. It’s extremely resistant to decomposition and typically lasts 10 years or more before it needs to be replaced.
Landscape fabric is tough enough to prevent weeds from growing through the bottom and coming up by your crops. Unlike landscape plastic, landscape fabric is permeable. This means it won’t block or hold water, ensuring your plants have the proper level of moisture at all times.
Final Thoughts
There are quite a few materials you can use at the bottom of your raised garden bed to separate your soil from the ground and deter weed growth. All of the materials above make excellent barriers, the best choice just depends on your budget and gardening preferences.