Does pressure-treated wood still contain arsenic?

Not the lumber sold for residential use today. The old treatment, chromated copper arsenate (CCA), which did contain arsenic, was phased out of residential lumber at the end of 2003 under an EPA agreement. Wood sold since 2004 uses copper-based preservatives like ACQ (alkaline copper quaternary) or micronized copper azole (MCA) instead, with no arsenic. If you are reusing old CCA lumber from before 2004, that is the material to avoid around food; new treated lumber is a different, arsenic-free product.

What is the safest wood for raised garden beds?

Naturally rot-resistant untreated woods are the safest and most popular choice: cedar and redwood resist decay for years without any chemical treatment, and are widely used for food beds. Untreated Douglas fir or pine is cheaper but rots faster, lasting only a few years. Beyond wood, metal beds (galvanized or aluminum) and composite lumber avoid the question entirely. If you use treated lumber and want extra reassurance, line the inside walls with plastic so soil does not contact the wood.

How do you line a treated wood bed to be safe?

Staple a heavy plastic sheet or pond-liner-grade material to the inside faces of the walls, above the soil line, so the growing soil never touches the treated wood. Line the sides only, not the bottom, so drainage and rooting into the ground below are preserved. This creates a physical barrier between any preservative and your soil, satisfying gardeners who want treated wood's longevity and rot resistance without direct contact. It is an easy, inexpensive step that also slows the wood itself from rotting.

Is railroad tie or old treated wood safe for garden beds?

No — avoid both around food. Old railroad ties are typically soaked in creosote, a preservative the EPA notes is not approved for residential use and which can leach harmful compounds, so they are a poor choice for vegetable beds. Reclaimed treated lumber from before 2004 may be arsenic-containing CCA wood. When you cannot verify what a piece of salvaged wood was treated with, keep it out of food-growing beds and use cedar, untreated lumber, metal or composite instead.

Is Pressure-Treated Lumber Safe for Vegetable Beds?

Q: Is modern pressure-treated lumber safe for raised vegetable beds?

The general consensus among extension sources is that modern copper-based treated lumber (ACQ, MCA) is low-risk for vegetable beds — the copper binds tightly in the wood and leaches minimally, and studies find little uptake into produce. Some gardeners still prefer to avoid any treated wood around food out of caution, and lining the inside faces with heavy plastic is a simple way to add a barrier. But the arsenic concern that drove the original worry no longer applies to lumber sold today.

Written & researched by Elena Marsh Gardening & Landscaping Editor

Updated October 2026

Close-up detail of the material being worked in a raised beds & planters project, in warm late-afternoon light

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Modern pressure-treated lumber is generally considered safe for vegetable beds, because it no longer contains arsenic. The old arsenic-based treatment, CCA (chromated copper arsenate), was phased out of residential lumber at the end of 2003: EPA records that manufacturers voluntarily discontinued CCA-treated wood products for homeowner uses in December 2003. Wood sold since 2004 uses copper-based preservatives — ACQ or micronized copper azole — that bind tightly in the wood and leach minimally, and studies find little uptake into produce. Some gardeners still prefer to avoid treated wood around food and line the walls with plastic; others choose naturally rot-resistant cedar, metal or composite instead.

Why the worry existed, and why it changed

The concern is real history, not myth. For decades, pressure-treated lumber was made with CCA, which contained arsenic, a genuine toxin, and there were legitimate questions about it leaching into garden soil and being taken up by food crops. That is why the caution persists in gardening lore. But the product changed: under a 2003 agreement with the EPA, manufacturers voluntarily stopped selling CCA-treated wood for residential uses, and by 2004 the lumber on store shelves had switched to copper-based preservatives with no arsenic. The wood you buy today is chemically a different material from the wood the original warnings were about — which is the key fact the old advice often misses.

Three-quarter view of a person's hands pressing seedlings into dark soil in a timber raised bed, in bright midday sun

Is the modern copper-based lumber safe?

The consensus from extension services is that modern ACQ and MCA treated lumber is low-risk for vegetable gardening; Oregon State Extension reviews the question specifically for raised beds and identifies copper azole, micronized copper azole and alkaline copper quaternary as the preservatives on consumer lumber today. Copper is the active preservative, it binds tightly within the wood, and what little migrates stays close to the wood surface rather than spreading through the bed; research on produce grown near it finds minimal uptake. Copper is also far less concerning to humans than arsenic. That said, "low-risk" is not "zero," and gardeners vary in how cautious they want to be around food. Those who prefer an extra margin can line the inside walls, which removes soil-to-wood contact entirely — a reasonable belt-and-suspenders step, not a necessity.

Golden-hour view of a person's hands pressing seedlings into dark soil in a timber raised bed

What are the alternatives?

If you would rather sidestep the question, several materials do the job without any treatment chemistry — Oregon State Extension names cedar and redwood as the long-lasting, safe framing choice for edible beds.

Material	Rot resistance	Notes
Cedar / redwood (untreated)	High, naturally	Popular food-safe choice; lasts years
Douglas fir / pine (untreated)	Low	Cheap but rots in a few years
Modern treated lumber (ACQ/MCA)	High	Low-risk; line walls for extra caution
Metal (galvanized, aluminum)	Very high	Avoids the wood question entirely
Composite lumber	Very high	No chemicals; higher cost
Old CCA wood / railroad ties	—	Avoid around food

Overhead view of a person's hands pressing seedlings into dark soil in a timber raised bed, in warm late-afternoon light

What to actually avoid

Two materials deserve a clear no around vegetables, regardless of where you land on modern treated lumber. Old railroad ties are usually saturated with creosote, which EPA restricts to certified applicators treating outdoor wood such as railroad ties and utility poles, and which is not sold to homeowners — keep them out of food beds. And reclaimed treated lumber from before 2004 may be arsenic-containing CCA wood; when you cannot verify what a salvaged board was treated with, do not use it for growing food. The safe rule for uncertain wood is simple: if you do not know what is in it, keep it away from your vegetables and reach for cedar, untreated lumber, metal or composite instead.

The bottom line

Modern pressure-treated lumber (post-2004, copper-based) is considered low-risk for vegetable beds; line the walls with plastic if you want extra reassurance, and avoid old CCA wood and railroad ties. Many gardeners simply choose cedar or metal to skip the question — our best raised garden bed and best metal raised beds roundups cover both, and how long metal beds last compares longevity. On wall lining, see lining a raised bed.

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