Can You Use Treated Wood For a Garden Box?

February 2, 2023 0 Comments

can you use treated wood for a garden box
If you’re concerned about using pressure-treated wood for a raised garden, you have plenty of alternatives. Bricks, concrete blocks, stone, and wire mesh are all good choices.

However, if you’re worried about chemicals leaching into the soil from treated lumber, you should avoid them entirely. Use untreated or rot-resistant lumber instead.


Creosote is a chemical compound that was once used to preserve wood products like railroad ties. It is derived from coal tar, and it is composed of various chemicals. It is considered to be a probable human carcinogen and can cause respiratory tract irritation. It can also be ingested by humans through contaminated foods or water and has been shown to cause skin burns and other problems.

Fortunately, modern treated lumber is a much safer option. It contains a variety of chemicals designed to prevent rotting and keep it from becoming damaged by termites and wood bees. It is also a more environmentally friendly option because it doesn’t leach into the soil as the old version did.

However, some gardeners are still concerned about the use of creosote-treated wood for their gardens. They worry that the creosote could harm their plants, so they avoid using it.

Some retailers like Home Depot and Menards sell used creosote-treated railroad ties, but they should be avoided. They are not a safe alternative for use in a garden box because they may contain creosote, which is toxic to people and pets.

According to the Agency for Toxic Substances and Disease Registry, creosote can pose serious health risks to individuals who are exposed to it for long periods. It is a carcinogen, and it can cause respiratory tract damage and gastrointestinal problems. It can also cause a skin rash and chemical burns of the eyes and mouth, and it can interfere with normal brain function and cause convulsions.

Other concerns about creosote-treated wood include its impact on wildlife. Some research has shown that creosote-treated wood has the potential to poison fish, frogs, and other aquatic animals. It can also be absorbed into the tissue of plants and eaten by insects, birds, and small mammals.

Another concern about creosote-treated lumber is that it can be a fire hazard. If a large amount of creosote-treated lumber was burned in a fireplace or wood stove, it would form a dense black substance that can be difficult to extinguish. This creosote can then enter your house through the chimney and re-ignite a fire.


CCA-treated wood is widely used in construction projects, such as telegraph poles, decking, garden edging, and handrails. It is also commonly used in playgrounds, children’s cubby houses, and public picnic tables.

Pressure-treated wood is usually treated with a variety of chemical preservatives to prevent rot and decay. The chemicals are generally designed to make the wood resistant to wood fungus, borers, and termites.

The chemicals include arsenic, chromium, and copper. As a result, some gardeners worry about whether plants grown in raised beds near CCA-treated lumber could accumulate levels of these elements that would exceed the safe dietary intake for people who eat the plants.

Fortunately, there are alternatives to using wood with arsenic, chromium, or copper for gardening. The alternative treatments are known as ACQ or alkaline copper quaternary (ACQ) and do not contain any toxic arsenic or chromium.

ACQ is a treatment that combines micronized copper with tebuconazole, which is a fungicide. Manufacturers of these treatments claim that their lumber won’t leach any toxic copper into the soil, which is important when you want to use it in a raised garden bed.

You can reduce exposure to these chemicals by using a plastic liner between the treated wood and the soil in your garden. You should also avoid using wood that has been treated with creosote, pentachlorophenol, and coal tar derivatives. These chemicals have a strong odor and are irritating to the skin and eyes.

If you must use CCA-treated lumber in your garden, you should cover it with heavy plastic. The plastic should be impervious to water and will keep the chemicals from seeping into the soil.

Another way to minimize exposure is to plant vegetables such as carrots, radishes, and turnips at least 12 inches from the wood. As Cr and Cu concentrations are greatest in the soil immediately adjacent to CCA-treated wood.

Soil that is in contact with CCA-treated wood will have much higher concentrations of As, Cr, and Cu than plant tissues. This is why it is recommended to thoroughly wash all soil from vegetables grown near CCA-treated wood before eating them.


There are several reasons to avoid using pressure-treated wood in a garden box, or any raised bed. One of the most important is that it is a hazard to your health and the environment. Another is that it may contaminate the soil.

The reason that CCA wood has been banned from residential use is because of the leaching of arsenic into the ground and people’s food supply. The newer preservatives CA and ACQ are much safer than CCA, but they can still pose some risks.

For example, copper-based preservatives, including the two commonly used for pressure-treated lumber, ACQ, and CA, can corrode metals like nails. This process is called galvanic corrosion. It can also cause the performance of shear walls to degrade.

This is a problem for raised beds because you want to be sure that the soil around the base of your raised bed doesn’t have to deal with the chemical exposure of the wood. This is especially true if you plan to grow fruit or vegetables in the raised bed.

The solution is to use a different type of wood in the raised bed or to cover it with a non-corrosive material. This could be cardboard, netting, or even plastic sheeting. You can also place the raised bed on top of a layer of mulch to keep the moisture in the soil.

In addition, it’s best to use wood that is locally sourced. If you can, consider wood that is FSC-certified. This organization is an international non-profit that promotes responsible forest management and encourages the purchase of wood from well-managed forests.

If you can’t find local, sustainably managed wood, you could use recycled lumber. However, this is not always a safe option because it’s likely that the recycled lumber was treated with Penta.

As a result, the Penta-treated wood will be highly toxic to you and your plants. In addition, the chemicals that were injected into the wood can be released into your plants’ roots and the soil as they grow.

This is why it’s so important to use a safe fastener for your raised bed or garden box. You can find a variety of fasteners that are compatible with ACQ-treated lumber at your local hardware store or home center. You should only use screws that have been approved for ACQ-treated wood and are code compliant. You should also use a spacer material between the ACQ-treated lumber and the aluminum to prevent direct contact between the wood and the fastener.

Other Treatments

Using a wood box for a garden is an elegant way to display your favorite plants. Whether it’s a raised garden bed or an above-ground planter, a well-crafted box is an essential part of any gardening enthusiast’s arsenal. Choosing the right material for your project will go a long way in ensuring that your investment lasts as long as possible.

There are several options to choose from, but one of the most popular is treated wood. These treatments are designed to prevent rot and other common trees problems such as insect infestation and mold and mildew growth, while at the same time, they make for more durable garden boxes in the long run.

The best way to find out which treatment is proper for you is to consult a professional or do some research online. While some gardeners have a hard time with chemical-based treatments, modern versions are not only safe for the garden but are quite effective at deterring insects and wood decay. The best thing about these preservatives is that they are cost-effective as well.