All the extra time we have staying at home meant indulging in our favorite hobbies, like gardening. Gardening has become a trendy hobby once again, which means more and more people are looking for ways to elevate their gardens.

Adding several raised beds is one way to improve the look of your outdoor space. From our previous blog, we give you some of the factors to consider including the ideal size for raised beds. And before you build one or buy online, you have to know what kind of wood or materials the garden beds are made of. Remember, not all materials should be used for raised bed gardening. Knowing the materials is important, especially if you are quite the handyman and have plans to build the raised beds yourself.

Key Takeaways:

• It is important to know the materials you use for raised garden beds.
• Not all types of wood are good for building raised beds.
• The best materials to use are rot-resistant and avoid treated lumber.

Best Materials for Garden Beds

If you used the wrong materials, you might end up harming the plants, the soil, and your health. Toxic chemicals could leach into the soil, polluting your growing space and killing your precious crops. In this guide, let’s discuss the best and worst materials to use for raised garden beds.

Cedar and Redwood

The best raised bed materials are cedar and redwood. These materials are not only resilient, beautiful, and resistant to moisture, they also repel termites. One might think that wood is not a good material for raised beds because of exposure to moisture, but those made with cedar or redwood will last for years, even decades when properly cared for.

Between cedar and redwood, the latter lasts longer, and the reason for this, as some gardeners say, is the high concentrations of tannins. This goes especially for heart redwood. Cedarwood is readily available and is reasonably priced, but redwood can be expensive. When buying wood materials for raised beds, choose lumber with an FSC certification. The lumber should come from “responsibly managed forests that provide environmental, social and economic benefits.”

Fir Wood

Firwood is another excellent lumber to use as a raised bed. The lumber is moderately rot-resistant and resilient. Taking precautions will definitely extend the life of fir wood raised beds.

Regardless if you’re building the raised bed yourself or you’re getting a ready-made one, apply waterproofer on fir wood as an extra layer of protection from moisture and harsh elements. Also, keep the raised beds away from excess moisture. When taken care of properly, fir raised beds will last for 10 to 15 years. Depending on the quality of the wood, fir lumber lasts longer than cedarwood.

Hardwood

Hardwood is dense, durable, and strong - even more durable than softwood. It will last for decades when taken care of properly and is naturally resistant to moisture and rot. Teak, maple, beech, walnut, and oak are hardwood. They are beautiful, though quite expensive. But if you really want to invest in gorgeous - and long-lasting - raised garden beds, you can’t go wrong with this material.

Untreated Wood

Untreated wood is ideal for garden beds because they’re sturdy and beautiful. However, these do not last as long as hardwood and softwood like cedar and redwood. Still, the material should last a few years, especially if you take care of it. Rotting sections could always be replaced, and untreated wood is affordable. You can always upgrade to hardwood and softwood over time.

Natural Rocks

Rocks make terrific material for raised garden beds because they’re easy to source, they look good in any garden - even in a contemporary garden, and they’re virtually weatherproof. Rocks come in different shapes and sizes, so finding the right one will take a lot of experimenting. But once you’ve found the correct type of rock for a garden bed, it’s just a matter of sourcing the material and hauling the rocks to the garden site. Yes, it will be backbreaking, but making the raised beds using rocks will be worth it because the material is virtually life-proof.

One thing to remember: rocks, especially the decorative kind, can be expensive. Unless you have plenty of rocks to use on your property, buying rocks is expensive.

Bricks

Bricks make a beautiful albeit unconventional raised garden bed material. It’s also pricey depending on the type of brick you’ll use. You can always recycle bricks if you have lots of them on your property. Raised beds made from bricks will last forever and a day with minimal to zero maintenance.

Cement Blocks

An excellent alternative to bricks are cement blocks. Cement particles are not dense, so the material promotes proper drainage. Although cement blocks do not look as good as traditional bricks, these are extremely hardwearing and low maintenance. What you can do is have them made into brick-sized blocks and paint them red so they’ll look like bricks.

Materials to Avoid Using in Raised Beds

Cinder Blocks: Cinder blocks are made from cement and cinder or fly ash. Fly ash is laden with heavy metals like mercury, arsenic, and lead, which can leach into the soil and contaminate your crops.

Railroad Ties: This is a common raised garden bed material in the US. Avoid railroad ties at all costs because the wood pieces are treated with creosote. Creosote is a type of oily wood preservative made from coal tar. The oil mixture contains 300 different chemicals, many of which are harmful to human beings and the soil.

Old Tires: Also used as garden bed materials in the past, mainly when growing potatoes. Although old tires should be recycled, these shouldn’t be made into raised beds because they contain heavy metals that could leach into the soil. You can recycle old tires but never use them to grow food.

Wood Pallets: Most pallets are made from lumber treated with methyl bromide, a known endocrine disrupting chemical. Some wood pallets are made from untreated lumber, but you have to be absolutely sure about this before using it to make raised beds. Most pallet producers stopped using methyl bromide in 2005, but older pallets are still unsafe to use. If the pallet has an “HT'' stamp, it’s heat-treated, which means it’s safe to reuse for gardening. If the pallet doesn’t have any identifying stamps, assume that it’s chemically treated.

Pressure-Treated Lumber: Pressure-treated lumber is used for making outdoor furniture and decks. It offers added protection from bugs and moisture. However, it is unsafe to use as a raised bed material. Pressure-treated wood is treated with chromate copper arsenate (CCA). Over time, CCA releases arsenic into the soil. While newer lumber is not treated with CCA, it’s still treated with harmful chemicals like copper azole (CA-B) and alkaline copper quat (ACQ). These chemicals are not as toxic as CCA but still able to leach into the soil.