DIY tips: The best material for making a raised garden bed you design on your own

Show Caption

Growing in raised beds can be a convenient method for overcoming challenges associated with in-ground gardening, such as poorly drained soil, rocky soil, heavy-clay soil, contaminated soil or excessive slope.

Raised beds tend to be more productive than in-ground beds because the soil is less compacted, has better drainage and warms and dries earlier in the spring, allowing you to start gardening earlier in the season.

Raised beds are also often easier to maintain than in-ground beds, particularly for gardeners with limited mobility. Raised beds typically have lower perennial weed pressure because of the soil used in the raised bed and the density of planting.

Raised beds can be used to plant vegetables, flowers, herbs and herbaceous perennials.

One of the questions I am often asked by gardeners who have never grown in a raised bed is what type of materials are best to construct a raised bed. There are many different types of materials that can be used for a raised-bed garden, so let’s take a look at some of the options.

Wood options

Many gardeners choose wood to construct raised beds as it can be a less costly building material than some others, and for its versatility in any bed design or size.

While inexpensive untreated pine lumber can be used to construct raised beds, rot-resistant cedar will be more durable and have a longer lifespan.

Treated lumber is an even better option for building raised garden beds simply because of its lifespan. Even though treated lumber will cost more up front, you won’t have to replace boards or entire beds after just a few years if you use treated lumber.

Newly purchased treated lumber is safe for garden beds where food crops will be grown as copper compounds are now used to treat lumber.

Older treated lumber was treated with arsenic or creosote compounds, making it unsuitable for bed construction for food crops. For this reason, we never recommend that gardeners utilize scavenged or repurposed lumber for raised-bed construction. Likewise, used railroad ties should never be used to construct garden beds for food crops.

Stone options

Different types of stone or concrete materials can be used to construct raised garden beds including brick, concrete blocks, stone pavers and even large rocks. Unlike our recommendation to not use salvaged lumber to construct garden beds where food crops will be grown, salvaged or repurposed bricks and concrete blocks are perfectly acceptable materials to use when constructing garden beds for food crops.

One long-term challenge with using bricks or concrete blocks to construct raised garden beds is that these materials tend to shift over time due to the natural freezing and thawing cycles of soils. If you build a garden bed with more than one layer or course of bricks or concrete blocks, it may be best to use cement or mortar between the layers to prevent this movement.

Metal options

One of the most popular materials right now for raised garden beds seems to be metal. There are many different raised-bed kits you can buy which use different types of metals. Beds made of metal will be very durable and will require little maintenance. Some gardeners seek out metal for its industrial-chic design aesthetic.

One metal option I have found to be very durable and simple to use for raised beds is a galvanized-steel livestock water tank. We have been using these tanks for raised beds on the OSU campus farm for about eight years with great success.

These tanks do not rust, and after eight growing seasons, they look as new and shiny as they did when we first filled them with soil. These tanks come in many different sizes and can be purchased online or at local farm supply stores.

There are also many different raised-bed kits made with different metal materials on the market right now. I would recommend kits which use galvanized steel, as these materials won’t rust and will last longer.

Plastic options

Raised-bed kits which use plastic materials for their construction have not held up well in the outdoor environment historically. Some of these materials were easy-to-crack and tended to bend and bow due to the freezing and thawing cycles.

Just recently, however, I have seen raised-bed kits on the market which utilize a thicker and higher-grade plastic, and these products seem to be more durable and even more decorative than older plastic-bed kits.

Correct soil and site

Whatever type of material you choose for your raised bed, be sure to select the correct site and use the correct soil. Choose a level site which gets a minimum of six to eight hours of direct sunlight and is away from large mature trees which may cast a shadow on the bed, particularly during the critical exposure period of morning through afternoon.

Native soil from the yard may not be the best soil to place in your raised bed, particularly if the native soil is compacted, rocky, poorly drained or composed primarily of clay. It's best to purchase lighter raised-bed soil to fill your bed.

For a complete guide to constructing and managing raised garden beds, go to extension.osu.edu/today/raised-bed-planting.

Mike Hogan is Extension Educator, Agriculture and Natural Resources and associate professor with Ohio State University Extension. Reach Mike at hogan.1@osu.edu.