How to Line Raised Garden Beds to Stop Tree Roots

Learn how to line raised garden beds to block tree roots, protect your plants, and keep your soil healthy with this simple method.

Tree roots in a mass within a raised garden bed

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If you’re wondering what to put under a raised garden bed to stop weeds or tree roots, using the right liner is essential…

Am I a fan of plastic? No. Am I a fan of fabric garden liners? No… but Yes.

I am a fan of harvesting from my garden and eating organically grown produce. If a fabric liner allows me to do that than I can stand behind that product. Tree roots in my garden beds have prevented me from growing in them in previous garden seasons. Last year I was unable to grow in two of my front raised beds due to the tree innervation. It was not devastating to our overall harvest but did prevent me from growing onions and a second crop of green beans.

Don’t be me and have your trees ruin your garden.

Freshly picked green beans in a metal colander in a bush green bean patch.

Tools You May Need

Shovel
Wheel Barrow
Weed Control Fabric
Plastic Cap Nails
Pickaxe
Hammer
Tarp

Top Tips for Lining Raised Garden Beds

Heavy Material– Opt for a liner that is .5mm thick. This is a heavier material that will help prevent arial roots from spreading into your raised garden bed. This is the one we used!
Plastic Cap Nails– A type of roofing nail, these nails (as the name suggests) have a plastic cap around the nail head. We used these to help secure the landscape fabric to prevent the liner tearing under the weight of the soil and regular wear and tear. I (or mainly my husband) am not interested in doing this project again in these same beds.

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What to Put Under a Raised Garden Bed

(liners compared)

There are multiple ways and reasons for lining raised garden beds. Your garden location and surrounding area will help determine the type of liner your raised beds require.

What to Put Under a Raised Garden Bed to Stop Pests

Chicken Wire: Gardeners may choose to line their garden beds with chicken wire or hardware cloth to prevent burrowing animals like moles and voles from entering their garden.

What to Put Under a Raised Garden Bed to Stop Weeds

If weeds are your main concern in your garden (Not Trees) then placing a layer of landscape fabric or cardboard on the bottom of your bed will help prevent weeds popping through.

Landscape Fabric allows for drainage so your plants will not be waterlogged but it does not break down over time so you will be limited by crops depending on the depth of your bed. I would recommend building a raised bed at least 12″ deep. This will allow you to garden most anything in your beds.
Cardboard is similar to landscape fabric in that it will create a barrier for weeds but cardboard will break down over time allowing your raised bed soil and the earth below to integrate. I lined all of my back garden with cardboard and love it.

What to Put Under a Raised Garden Bed to Stop Tree Roots

When gardening, proximity to trees is always something to consider. Now typically I would say avoid it as much as possible, but not all of us can change the landscaping around our house for the convenience of gardening. If you’re a beginner gardener learn from my mistake and line your beds at the start.

A heavy duty landscape fabric like this one, double lined should prevent arial roots from taking over your garden.

Another thing to note about trees. Arial roots are looking for water, so if they wreak havoc in your garden beds chances are your tree is under watered (I will now be watering mine). Line your beds but also deep water your tree to prevent arial roots traveling back to your garden.