What should go on the bottom of a raised metal garden bed?

If you are considering filling a metal raised garden bed, you should plan to put something under it. Not only does it provide adequate drainage, but it also protects your chosen garden bed soil mix from direct sunlight and prevents weed growth. Here are some fillers you might use for the bottom of your garden bed:


Those looking to place organic material at the bottom of a raised bed garden may consider using a wood chip mulch. While they don't provide the same drainage as gravel, they can be easily added in a way that still provides good water flow, and over time they will break down, replenishing the native soil below. However, you should try to avoid pressure-treated wood as the chemicals may still seep into the soil. So make a thick layer of organics, put wood chips on the bottom, then a layer of grass clippings, hay, and leaves.

gravel or river stone

Other popular choices for the bottom of a metal raised garden bed are pea gravel or river stone. It provides drainage, allowing any excess water to drain from the roots of the plant. Because it doesn't break down, it lasts longer than other materials that are more prone to decay over time. However, it can be more expensive.

pine needles

Pine needles have many benefits. They are a viable option for the bottom of metal raised garden beds because they tend to retain moisture and decompose slowly, which means they improve the soil of the garden bed over time. Pine needles also provide a natural mulch that can help keep your garden hydrated when it's hot and dry outside.


This can be a great option for using landscape fabrics. This probably won't last much longer than the latter, but it can stay under a raised garden bed before completely disintegrating. Because of the gaps between its threads, it allows water to pass through and provides better drainage for your metal raised garden bed. It is made from jute plant fiber, so it is eco-friendly.

Geotextile or landscape fabric

Another popular option, especially for those looking to minimize time spent maintaining garden beds, is landscaping fabric. This fabric, available at most home improvement stores, provides good drainage and prevents weeds from growing from the bottom of a metal raised garden bed. Landscape fabrics are not as durable as gravel or river stone, but are relatively inexpensive.