The Safety of Materials Used for Building Raised Beds (2024)

FAQs

The Safety of Materials Used for Building Raised Beds? ›

Treated Wood Raised Garden Beds

Build your raised bed with a decay-resistant type of wood, such as cedar, black cherry, oak (bur, chestnut, post, white), black locust, Osage orange, or redwood. (Source: USDA Forest Products Lab) Use a non-wood material such as stones, concrete blocks, bricks, or synthetic lumber.

Furthermore, galvanized garden beds are non-toxic and safe for plants, animals and humans alike. As such, they're an ideal choice for those looking to create a sustainable garden that will last for years to come.

He stated in a bulletin titled, Treated Wood in Raised Bed Gardening, “Scientific evidence and data have shown that using pressure treated wood for raised bed or box gardening is safe to adults and children in terms of the plants grown and used in these containers.” He further explains, “All chemicals in consumer ...

You don't have to build the frame out of wood for your raised bed garden to be truly organic. Other options are bricks, flagstone, or even large river rocks. (Add a non-toxic garden bed liner to hold the soil in place.) Steer clear of concrete; it may leach into your soil and alter soil acidity.

There is a lot of research on this because of how often concrete is used for everything. There is some leaching but it is extremely slow and extremely low levels. This is why it is allowed to be used for drinking water tanks and pipes.

The safest wood to use for vegetable container gardens is cedar. It resists rot and lasts a long time, but it is pricey. You can safely use other kinds of untreated hardwood to build raised beds, but your project will rot and warp in a few years, depending on the wood.

Wood treated with Chromated Copper Arsenate (CCA) is NOT considered safe. CCA is a well-documented health hazard, making it unacceptable for a raised garden or for contact with anything edible.

Ideally, you want to select pallets marked with and HT stamp. The HT stamp signifies that the wood on the pallet is heat-treated rather than chemically treated. Avoid chemically treated pallets to keep you, your family, and your vegetables safe from toxic contaminants.

Well, the answer is yes. They are safe for gardening. The zinc coating used on metal raised modular raised garden beds needs to break down the acidity before it can start seeping into the soil. Most garden soils have a neutral pH, so zinc will have little effect on your garden.

Do galvanized steel raised beds get too hot? ›

The answer is a resounding NO! Depending on the beds you are using, elevated metal beds do not get too hot. Birdies Raised Beds are the garden beds that I use and I have not had problems with plants burning up and I LIVE IN DESERT ARIZONA.

In their finished form, no, galvanized steel buckets, tubs and other galvanized household products present no toxic risk to adults, children, plants or animals.

Even though the new pressure-treated woods are considered safe, Wolmanized Outdoor, according to its Web site, does not recommend using pressure-treated wood where the preservatives may become a component of food. Its recommendation is to use an impervious liner between the wood and the soil.

Do plants absorb the preservative in pressure treated wood raised garden frames? Yes, plants can absorb these preservatives, but tests have shown that the amount of preservative leached from the newer PT wood products is so low that it is virtually undetectable.

The safety of pressure treated lumber for raised bed gardens has been examined by several researchers. From what I've seen, the consensus is that the chemicals do leach out of the wood into the soil and are uptaken by the plants in very small amounts.

Cedar or redwood are two great options for wood as they are naturally rot-resistant and won't leach harmful chemicals into the soil. Using reclaimed wood can also be a sustainable choice, but it's essential to ensure it hasn't been treated with toxic preservatives.

The treated wood can leach toxic chemicals for many years, so it would be wise to assume that the wood remains toxic. That said, there are a number of strategies you can use to minimize exposure of your raised veggie garden to the treated wood, as noted below.

The cons of raised beds

The main downside of raised beds is the work and expense of creating them in the first place. You don't have to use borders (soil can be raked into raised beds each season), but if you do, you'll have to acquire the wood, blocks, or stone.

Cinder blocks haven't been mass produced with fly ash in the U.S. for 50 years, though. The cinder blocks that you buy in the store today are actually concrete blocks and totally safe. Unless you're using antique cinder blocks, there should be no reason to worry, especially when cinder block gardening for vegetables.

A cost-saving alternative to Cedar, treated-wood products work very well when constructing raised bed gardens. Raised beds offer many benefits and advantages for gardeners: Improved drainage. Easier to improve soil quality.

Is plywood safe for garden beds? ›

Drawbacks of Gardening with Plywood Boxes

As plywood is not a naturally porous material, it can be hard to keep the soil moist and the plants healthy. Additionally, plywood can be prone to warping and cracking over time, which can be a problem if you are not able to inspect and repair your boxes regularly.

Regular pine board can be used as well. Pine will last an average of 5 years as a raised garden bed, and redwood will last more like 10 years. Landscaping block and brick can make for a good raised bed as well.

A depth of 8 – 12 inches will suffice for most gardening situations. Because of the excellent drainage properties of raised beds, it is possible to grow an abundance of vegetables in a limited amount of space.

As a final reminder, avoid lining your garden beds with plastic. Doing so prevents drainage and could drown your plants' roots with too much water. If you have a weed and pest problem, consider installing a combination of metal mesh and fabric or hardware cloth and cardboard to address both issues simultaneously.

Cardboard or newspaper: Cardboard is a great option if you are on a budget. You can line the bottom of your raised garden bed with cardboard and newspaper to deter pests and weeds. In order to minimize the amount of chemical substances, choose cardboard that has no tape and minimal markings.

We recommend buying high-quality, nutrient-rich soil in bulk. Or, you can make a soil mix with equal parts topsoil, organic materials (leaves, composted manure, ground bark), and coarse sand.

You can line your raised bed to make it more durable and to prevent toxics from leaching into the soil. For lining, use landscape fabric found at garden supply stores or cloth fabric from clothing. Avoid non-porous plastic, as it can retain too much water and discourage beneficial insects and worms.