If you want to use wood that is good for all seasons and protect your wood against rotting and insects use Pressure-treated wood. Pressure treated wood is usually used for mailboxes, swing sets, picnic tables and much more and you can buy it as lumber. It is best used when your wooden planter is in moisture environments or if there is contact with moist soil. It will protect your wood for around 20 years.

What is pressure treated wood?

Pressure treating is a process that forces a chemical preservative deep into the wood. The wood product is placed into a humongous cylindrical holding tank, and the tank is depressurized to remove all air. The tank is then filled with the preservative under high pressure, forcing it deeply into the wood. The tank is then drained and the remaining preservative reused. The wood is removed from the tank and prepared for shipment to your local lumberyard.

Can you safely use pressure treated wood for planters?

Can you safely use pressure treated wood for your wooden planters and for growing vegetables? Yes, you can use them for wooden planters but a big NO for using them for growing vegetables.
The most common preservative used for pressure treated wood, up until 2003, was chromated copper arsenate (CCA). This is a compound using arsenic as its primary rot protectant. The problem is that using this kind of pressure treated wood you will have a big chance of soil contamination. Resulting in poisoning the soil.

New Pressure treated wood

At this moment new preservatives like copper or chromium are used as the primary preservative replacing chromated copper arsenate (CCA). This changed the safety of pressure treated wood dynamic dramatically. The advantage of the new preservatives like copper or chromium is that they are not absorbed efficiently by the body. Working with this kind of treated wood is save but precautions have to be taken such as washing your hands and collecting the sawdust.
Plants can however absorb these preservatives, but tests have shown that the amount of preservative is so low that it is virtually undetectable.

Important tips

• DON’T use pressure treated wood planters for growing vegetables.
• Predrill any nail or screw holes within an inch of the end of the board and clean up all sawdust.
• Use only screws or nails that are galvanized and designed for use with the newer copper-based pressure-treated wood.
• Be sure to buy the correct grade of PT wood.
• Use ground-contact grade for raised gardens.
• Pressure-treated wood should not be burned.