The Best Materials to Put at the Bottom of Raised Beds

Gardeners' love raised garden beds as these elevated beds simplify plant care and help you make the most of your garden space. Raised beds improve drainage, minimize soil compaction, keep rats and other pests out of your plants, and help prevent weed growth. If they're built correctly using best-quality materials, they can last for many years. Raised gardens are usually filled with a rich, raised-bed soil mixture consisting of sand, compost, topsoil, and other soil amendments. However, to get the best results from raised bed gardening, you can add various other materials to the bottom of raised beds before adding the soil.

What to Put Under Raised Garden Beds

The materials placed at the bottom of raised garden beds form a barrier between the garden's soil and the ground. The right material can prevent weeds from growing, keep out toxins, and ensure pests stay in the ground and away from your garden. While you can fill raised beds with various materials from your home, it's important to use only food-safe materials in your kitchen gardens.

Here are the six best items to put at the base of your raised beds, and let's discover why these materials work so well.

1. Newspaper or Cardboard

Cardboard is a low-cost organic material to block weed growth below your garden beds. When you install a new raised bed, there is a strong chance that weeds, and grass are already growing in that area. Mowing these undesired plants lower to the ground lowers weed issues in your planting area, but grass and weeds will resprout if you don't control them. The best way to do this is to cover the area you've chosen for the bed with several layers of cardboard. Cardboard will decompose in around 4 to 6 months. It'll kill any remaining weeds before decomposing into the soil.

In addition to cardboard, you can also use newspaper to block weeds and prevent grass from regrowing in your garden beds. Newspaper is thinner than cardboard, so add it in thicker layers that are several sheets deep.

2. Weed Barrier Fabric

Weed barrier landscape fabric is the best weed blocker that ensures only your desired plants sprout. This organic material is super effective at keeping unwanted weeds from overtaking your favorite plants. Before putting the weed barrier at the bottom of your raised beds, remove all existing weeds from the location, level the soil, and then lay out your fabric. The fabric effectively blocks weeds, so they don't overrun your plants and allows water, air, and other beneficial nutrients to reach your plants.

3. Compost

Compost is not used on its own, but it is blended into the topsoil of a raised bed garden after the bottom part has been layered with other organic materials such as those mentioned above. However, you can add a few inches of compost to the base of your raised garden beds. This will save you a lot on soil orders, and your plants will benefit from the extra nutritional boost when the roots grow deeper into the compost layer.

Compost improves soil drainage, adds nutrients to soil, increases water retention, and enriches the soil by supporting beneficial soil organisms such as earthworms and microbes.

4. Wide Mesh Hardware cloth

If you struggle with weeds, rodents, groundhogs, and other burrowing animals in your garden, you should place hardware cloth across the bottom of raised garden beds before filling them with soil. This fine mesh material will keep weeds and digging animals out of your raised beds, but earthworms can pass through. Earthworms are nature's gardeners as they aerate and enrich the soil to benefit your plants.

When installing the garden bed, staple the hardware cloth to the bottom of the frame. Once in place, it'd serve its role for many years to come. This material is made of welded wire and is one of the effective ways to prevent animals from eating root crops, tubers, and bulbs.

5. Wood Chips and Mulch

Another best organic material to add to the base of your raised beds includes wood chips or mulch. Like sticks and twigs, wood chips and mulch degrade naturally and improve the soil as they decompose. However, do not apply thick layers of wood chips or mulch because these materials are dense and may interfere with drainage.

Wood chips are ground-up twigs, branches, and leaves. They are also a type of mulch, but they are thicker and more irregular in size than wood chip mulch and shredded mulch, so they break down slowly. When you obtain wood chips from a tree service, always inquire about the type of trees used to avoid unsuitable ones.

6. Autumn Leaves

Fallen leaves or leaf mold are another good organic filler for a raised garden bed before adding the soil. Decaying leaves contain microorganisms and worms that break down other organic materials. When they decompose, they add beneficial nutrients to the soil that help plants grow. Adding them to the bottom of raised beds is a free way to boost the nutrient content of your soil.

If possible, mulch fallen leaves before placing them in your beds. Also, avoid using leaves from trees like black walnuts, as they can interfere with the growth of plants such as tomatoes.

Benefits of Lining the Bottom of Your Raised Beds

Gardeners often add organic materials to the bottom of deep raised garden beds to fill space and to make up for the cost of soil. Layering pest and weed barriers, along with organic soil amendments, in raised beds helps plants grow better and makes beds easier to maintain in the long run. Best of all, many of the things you can use to fill the bottom of raised beds can be found for free from your garden, kitchen, or bin.

Experienced gardeners recommend lining raised beds for the following reasons:

• It improves soil retention.
• It prevents weed growth by separating weeds from the seeds.
• It insulates the soil and helps regulate temperature variations.
• It can repel burrowing pests such as moles and gophers that can harm your plants' roots.

Best Soil for Raised Garden Beds

One of the several benefits of raised bed gardening is that you have greater control over the soil. It is a significant benefit for homeowners with clay or hard soil, a yard with tree root issues, or ground pollution concerns. Soil is the foundation of your vegetable garden, and it should be healthy so that your plants can thrive. It is best to get high-quality, nutrient-rich soil in bulk. Or, you can make a quality raised bed soil mix with topsoil, soil amendments, organic materials like leaves, composted manure, ground bark, and coarse sand.

Read More: How to Fill and Plant in a Raised Garden Bed

What to Avoid in a DIY Raised Bed Bottom Lining

• Avoid using treated lumber chips and sawdust because they may contain harmful chemicals for edible plants.
• Don't use non-biodegradable materials like styrofoam, plastic, and synthetic fabrics, as they will not decompose.
• Never use paper or magazines with glossy inks. Printed materials may contain chemicals that are not safe for the kitchen garden.
• If you've persistent weeds or burrowing pests, always line the bottom of the bed with a weed barrier.
• Avoid using food scraps containing meat or dairy. These materials invite pests.

The Bottom Line

Whatever you choose to put on the bottom of your raised beds, make sure to add several inches of good-quality organic soil and compost at the top. If your garden has aggressive weeds or you want to increase drainage in clay soil, a permeable weed barrier landscape fabric is an excellent barrier choice for the base of your raised beds. A weed barrier at the bottom of your raised bed offers numerous benefits. It prevents weeds from growing up into the soil and keeps burrowing pests away from your plants' roots. Make sure there are no open spots, as this is an invitation to weeds.

Visit DripWorks' website to get the best-quality raised garden beds, soil amendments, garden tools, landscape fabric, and more gardening products.