Safety First! Wood Edging With Pressure Treated Lumber

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👋🏼Hi there.

Planning a garden edging project and considering your lumber options? You've probably come across pressure treated lumber (PTL) in your research – and for good reason.

PTL is a super popular choice for outdoor projects, from decks and fences to garden edging. It strikes the perfect balance between affordability, durability, and ease of installation that makes it an excellent choice for gardeners, landscapers, and DIYers.

Using PTL for common edging projects – containing mulch around flower beds, creating raised garden beds, defining borders along pathways – is a practical solution that can last for years with minimal maintenance.

Regardless of its convenience, many people have concerns about using PTL - which is a chemically treated product - in their gardens.

I'm here for that!

By the end of this post, you'll understand exactly what PTL is, how it's made, and safety considerations for garden use - garden edging use in particular.

Let's get to it!

Why Pressure Treated Lumber is Perfect for Outdoor Projects

There are many reasons why PTL is a go-to building material for outdoor projects. It ticks a number of boxes:

Affordable and Budget-Friendly

Cost is often the first consideration for any DIY project, and PTL delivers exceptional value.

Of all of the lumber that can be used in outdoor applications, untreated wood is the least expensive and least durable option, lasting two to four years depending on conditions.

For just a few dollars more per board PTL boosts your project's useful life by ten or more years rivaling more expensive options such as cedar and redwood.

📌 Learn about lumber costs. See our complete pricing guide for detailed lumber cost and durability comparisons: The Best Lumber For Garden Edging: Compare Pros & Cons".

This affordability makes PTL perfect for larger landscaping projects where you need significant amounts of edging material without breaking your budget.

Easy to Obtain Anywhere

One of the biggest advantages of choosing PTL is its availability. You can find it in quantities at virtually any lumber retailer including:

Big box stores: Because its useful for all sorts of projects, Home Depot, Lowe's, and other home improvement stores maintain PTL inventory. And it's competitively priced.

Local hardware stores: Your neighborhood hardware store often stocks PTL and - bonus - can provide personalized service and advice.

Lumber yards: Professional lumber yards typically offer PTL in the widest selection of dimensions and lengths, plus they often provide delivery services - sometimes for free.

Highly Customizable to Bring Your Vision To Life

PTL is available in a variety of dimensions and lengths enabling you to choose the perfect size for your project needs off the shelf.

It's also easy to work with using manual or power tools. Want to create geometric garden beds? Simple angled cuts transform straight boards into hexagons, octagons, or any shape your landscape design requires. Need subtle borders along pathways? Choose smaller dimensions for a clean, understated look.

And, since PTL is (chemically enhanced) wood, you can enhance the natural wood appearance through staining or painting to match your outdoor aesthetic perfectly.

📌 Garden design inspo is here! Project details and video - a showcase of all kinds of edging projects: DIY Garden Edging Ideas Made Simple With 2xEDGE".

Durable and Long Lasting

PTL used in outdoor projects including garden edging applications can last 10-15 years. This translates into less maintenance, repair, and replacing, providing lasting value.

And PTL is resistant to insect infestation and rot. Your garden borders will maintain their structural integrity and appearance season after season.

What is Pressure Treated Lumber?

Pressure-treated lumber is made from a variety of wood species, and what's available at your local lumber yard often depends on geography.

• Southern Yellow Pine is the most widely used species in the U.S., thanks to its excellent ability to absorb preservatives.
• In the western U.S., Douglas Fir is more typical.
• In the Pacific Northwest, you'll often find hemlock-fir or spruce-pine-fir (SPF) combinations.
• In Canada and the northern U.S., Red Pine and Jack Pine are commonly used.

Understanding how PTL is made helps explain why it performs so well in outdoor applications. Warning: technical explanations ahead!

The Pressure Treatment Process

The name "pressure treated" comes from the manufacturing process used to infuse wood with preservative chemicals. Here's how it works.

The pressure treatment process begins with kiln-dried lumber that's loaded into large cylindrical chambers called treatment vessels.

High pressure is the key to the process. The treatment vessel is sealed and a vacuum is applied to remove air from the wood cells. Then, liquid wood preservative is pumped into the vessel under high pressure.

This use of pressure forces the preservative deep into the wood fibers, far beyond what surface application could achieve. The pressure phase can last several hours, ensuring complete penetration throughout the lumber.

After the treatment process is complete, the lumber is removed and allowed to dry. The result is wood that's protected throughout its entire structure, not just on the surface.

Chemical Preservatives Used in PTL

Modern PTL relies on chemical preservatives that provide long-lasting protection against decay and insects, creating rot resistant wood.

The most common wood preservative used today include several copper-based formulations that have replaced older treatments.

The high level of copper in modern PTL is what gives many boards their distinctive greenish tint when new. (I always wondered about that greenish tint!)

Lumber intended for direct soil contact contains higher concentrations of preservatives than lumber designed for above-ground use.

Copper compounds are favored in modern treatments because copper provides excellent antifungal properties while being less concerning from an environmental standpoint than some older preservative systems.

Alkaline Copper Quaternary (ACQ) is one of the most widely used preservatives. It combines copper compounds with quaternary ammonium compounds to provide broad-spectrum protection against fungi and insects.

Copper Azole is another category of wood preservatives. It uses copper combined with azole compounds - azoles are antifungal agents. (Check the Wikipedia entry for all of the scientific details on azoles.)https://en.wikipedia.org/wiki/Azole

Is Arsenic Used in PTL?

I, too, have wondered about arsenic. Yes - it was used in older treatment methods. But today's residential PTL contains no amount of arsenic compounds.

Chromated Copper Arsenate (CCA) was in widespread use in residential lumber treatment until 2003. This meant that older PTL contained inorganic arsenic as a key component.

However, CCA PTL for residential use was voluntarily phased out by manufacturers in 2003.

Modern CCA wood is now restricted to industrial uses such as utility poles, dock pilings, and agricultural fence posts. (For more see this EPA article on CCAs and this 2004 article from Fine Home Building that reviews the newly formulated PTL at its release.)

Rest assured, the arsenic levels in lumber available at retail stores today are zero, as modern copper-based preservatives have entirely replaced CCA for consumer applications.

Regulatory Oversight and Standards

Multiple agencies provide oversight and set standards for PTL to ensure safety and effectiveness.

United States' Environmental Protection Agency (USEPA or EPA)

The EPA serves as the primary regulatory body for wood preservatives in the US. It registers all wood preservatives and sets guidelines for their safe use.

The EPA has thoroughly reviewed modern copper-based preservatives and approved them for residential use, including applications around homes and gardens. 

Industry Standards and Certification

The American Wood Protection Association (AWPA) develops and maintains standards for wood preservatives and treatment processes. These standards ensure consistency and safety across the industry. 

The Forest Stewardship Council provides additional certification for sustainably managed forest products, including some PTL options.

Health Risks and Safety Considerations

While modern PTL is significantly safer than the PTL produced with earlier processes, it's important to understand the health risks and safety concerns associated with any chemically treated wood product.

Primary Health Concerns

The primary concerns with today's PTL center around the chemical preservatives used in the treatment process.

Even though these are toxic chemicals by design (they need to kill fungi and insects), the risk to humans depends on the method and duration of exposure to the chemicals.

Health effects from PTL can come from three potential types of exposure:

• inhalation of dust during activities like cutting or sanding - the heavy metals present in the preservatives can become airborne during these activities;
• skin contact during handling; and,
• potential leaching of chemicals.

Health Risks in Perspective

Modern PTL presents much lower health risks than older CCA-treated wood. The copper-based preservatives used today are generally considered less toxic to humans while maintaining effectiveness against wood-destroying organisms.

Health concerns about leaching are generally minimal in typical garden edging applications, where the lumber is above ground and not in direct contact with plants or food sources.

Is Pressure Treated Lumber Safe for Garden Edging?

This is probably the most common question asked when considering using PTL in the garden.

For garden edging applications – where the lumber contains mulch, defines flower beds, or creates borders around ornamental plantings – modern PTL is generally considered safe by regulatory agencies.

The key distinction is between direct contact with plants versus use as a border.

When used as edging around flower beds, flower borders, or garden beds, the lumber typically doesn't come into direct contact with plant roots or edible parts.

Even though regulatory agencies consider modern PTL safe for this use, for vegetable garden applications many gardeners prefer alternatives like untreated cedar or composite materials to avoid any potential chemical leaching near food crops.

Additional Resources on PTL Safety

If you'd like to dive deeper into the safety concerns of PTL in the garden, here are helpful resources:

• Treated Wood in the Landscape, Clemson Cooperative Extension
• Is Treated Wood Safe in the Garden?, Oregon State University Extension
• Using Pressure-Treated Lumber in Raised Garden Beds, University of Minnesota Extension
• Are Pressure-Treated Woods Safe in Garden Beds?, Fine Gardening Magazine
• Pressure-Treated Wood and Raised Bed Gardens, Rutgers NJ Agricultural Experiment Station
• Micronized Copper Azole (MCA) Treated Wood FAQ, University of Florida / IFAS Extension
• Residential Uses of Preservative-Treated Wood, U.S. Environmental Protection Agency
• Copper Azole Treated Wood Safety in the Garden, Cornell University Horticulture Blog

Safety Precautions When Working with PTL

Taking appropriate safety precautions protects you during cutting, handling, and installation of PTL.

Essential Protective Equipment

Always wear eye protection and use a dust mask or respirator when cutting, sanding, or creating dust from PTL. The preservative chemicals can become airborne during these operations.

Wear gloves, and consider wearing long sleeves and pants, when handling PTL to minimize skin contact with the preservatives.

Basic Safety Practices

Always wash hands thoroughly after handling PTL, especially before eating or touching your face.

Work in well-ventilated areas when cutting or sanding to minimize dust accumulation.

Clean up wood chips and sawdust promptly, and dispose of them with regular trash rather than composting or burning.

📌 Before You Grab a Shovel To Dig a Trench -
Check out our comprehensive two-by lumber installation guide, "How To Install Landscape and Garden Edging (DIY)" for complete step-by-step install instructions. Plus explore a variety of garden edging options.

Choosing Dimensional Pressure Treated Wood for Garden Edging

With so many edging materials available, why choose dimensional PTL over another type of wood?

Wood Comparisons

Within wood types, PTL competes with several alternatives:

Both pressure-treated and untreated wood offer a natural look, and you can paint or stain either to match your garden design. But the real advantage of PTL is durability: for just a few dollars more per board, you’ll get significantly more years of reliable performance—often doubling or tripling the lifespan compared to untreated wood.

Cedar and redwood are beautiful and long-lasting, but pressure-treated lumber (PTL) is hard to beat on value. An 8-foot PTL 2x4 typically costs just $5 to $8 and lasts 10 to 15 years. In contrast, cedar runs $10 to $15 for the same size and lasts 15 to 20 years; redwood can cost $15 to $20 and lasts 20 to 25 years. While it’s true that cedar and redwood outlast PTL, the cost-per-year of service is often lower with PTL—making it a smart, budget-friendly option for edging that will hold up well for a decade or more.

Landscaping timbers (or landscape timbers) offer rustic appeal but can be harder to work than dimensional lumber. They're also typically available only in 8-foot long pieces. PTL is available in a number of off-the shelf lengths giving you many more options to choose from.

Railroad ties provide substantial mass but are extremely heavy, expensive to purchase and to have delivered, and may contain creosote preservatives that aren't suitable for garden use.

📌 Wondering About Your Lumber Options? 
Check out: Garden Edging with Two-by (2x) Lumber: The Complete Guide.

Two-by (2x) PTL Advantages

Natural wood appeal combined with enhanced durability makes PTL an ideal choice for many garden projects. Wooden edging made from PTL provides the natural look that many gardeners prefer while offering practical longevity.

Wood edging projects benefit from PTL's resistance to the moisture and soil contact that quickly deteriorates untreated materials.

Wood products in general offer environmental advantages as renewable resources, and PTL extends the useful life of this renewable resource.

Design and Aesthetic Benefits of PTL

PTL starts out with an attractive brown color that weathers to a natural silver-gray over time. This natural-looking border blends seamlessly into most landscape designs.

The straight line definition that lumber provides creates clean landscape design elements that enhance rather than compete with your plantings and other features.

For gardeners who prefer the natural look over manufactured edging products, PTL provides an excellent choice that ages gracefully in outdoor environments.

Frequently Asked Questions (FAQs)

What chemicals/preservatives are used in modern pressure‑treated lumber, and are they safe?

Modern pressure treated lumber uses copper-based preservatives like Alkaline Copper Quaternary (ACQ) and Copper Azole, which combine copper compounds with other agents to protect against rot and insects. These copper-based treatments are considered significantly safer than older formulations and have been approved by the US Environmental Protection Agency (EPA) for residential use, including applications around homes and gardens. FYI: The copper content gives new pressure treated lumber its distinctive greenish tint.

Does pressure treated lumber still contain arsenic?

No, modern residential pressure treated lumber contains zero arsenic. The older Chromated Copper Arsenate (CCA) treatment that contained arsenic was voluntarily phased out by manufacturers in 2003 and is now restricted to industrial applications like utility poles and dock pilings. Today's pressure treated lumber available at retail stores uses only copper-based preservatives with no arsenic compounds.

Is pressure treated lumber safe for children and pets?

Modern pressure treated lumber is generally considered safe for use in backyards where children and pets are present, as the copper-based preservatives used today pose minimal risk during normal exposure. However, it's important to prevent children and pets from chewing on or ingesting the wood, and to wash hands - and feet - after direct contact with the lumber. For garden edging applications where the lumber serves as borders rather than direct contact surfaces, the risk is minimal under normal use.

What safety precautions should I take when working with pressure treated lumber?

Always wear eye protection and a dust mask when cutting or sanding pressure treated lumber, as the preservative chemicals can become airborne during these activities. Wear gloves and consider long sleeves and pants when handling the lumber to minimize skin contact. Always wash your hands thoroughly after handling the lumber - especially before eating. Work in well-ventilated areas and clean up wood chips and sawdust promptly, disposing of them with regular trash rather than composting or burning them.

Is modern pressure‑treated lumber safe for raised vegetable garden beds?

Most university extension services and gardening experts recommend avoiding pressure treated lumber for raised vegetable garden beds due to potential chemical leaching near food crops. While the US Environmental Protection Agency (EPA) considers modern copper-based preservatives safer than older formulations, many gardeners prefer alternatives like untreated cedar or composite materials when growing edibles. (Info about alternative types of lumber is available in our lumber options post.) The concern centers on minimizing any potential chemical exposure to plants that will be consumed.

Can treated lumber leach chemicals into the soil and affect edible plants?

Yes, pressure treated lumber does leach small amounts of copper and other preservative chemicals into surrounding soil over time, though the amounts are typically minimal. Research shows that while copper levels may increase in soil immediately adjacent to treated wood, the impact on plant uptake varies by plant type and soil conditions. This is why many experts recommend maintaining distance between treated lumber and edible plant roots.

Can I plant directly against pressure‑treated wood (e.g., beds touching the boards)?

For ornamental plants and flowers, planting directly against pressure treated lumber is generally considered acceptable by regulatory agencies. However, for edible plants, it's recommended to maintain some distance between the treated wood and plant roots or use a barrier like landscape fabric. The key is avoiding direct root contact with the treated lumber, especially for vegetables, herbs, and other plants you'll consume.

Can I use pressure treated lumber for herb gardens?

Using pressure treated lumber for herb garden beds is not recommended since herbs are consumed and often grown in close proximity to edging materials. The concern is that even small amounts of chemical leaching could affect plants that will be eaten, especially herbs that may be consumed in larger quantities. Consider alternatives like cedar, composite materials, or untreated wood for herb garden applications. (More about  lumber options is available in our lumber comparison post.)

What's the difference between using pressure treated lumber for ornamental vs. edible gardens?

The key difference lies in the intended use and proximity to consumable plants. For ornamental gardens, pressure treated lumber used as pathway edging or flower bed borders poses minimal risk since it's not in direct contact with plants you'll eat. However, for edible gardens, the concern increases because vegetables and herbs may absorb trace chemicals through their root systems. Pressure treated lumber is considered safer for defining walkway borders and ornamental bed edges than for containing soil where food crops will grow.

Does pressure treated lumber leach chemicals into soil?

Yes, pressure treated lumber does leach preservative chemicals into soil, but typically in very small amounts. The leaching rate depends on factors like moisture, soil pH, and age of the lumber, with newer lumber generally leaching more initially. Modern copper-based preservatives leach at much lower rates than older arsenic-based treatments, and the chemicals tend to bind to soil particles rather than migrate far from the source.

How long does pressure treated lumber last in outdoor applications?

Pressure treated lumber typically lasts 10-15 years in outdoor applications, making it significantly more durable than untreated lumber which only lasts 2-4 years. The exact lifespan depends on factors like moisture exposure, soil contact, and maintenance, with properly maintained pressure treated lumber potentially lasting toward the upper end of this range. This longevity makes it a cost-effective choice for garden edging projects where you want durability without the higher cost of cedar or redwood. (Lumber costs are detailed in our lumber comparison post.)

What's the difference between ground contact and above-ground pressure treated lumber?

Ground contact pressure treated lumber contains higher concentrations of preservative chemicals and is designed for direct soil contact applications like fence posts and deck footings. Above-ground pressure treated lumber has lower chemical concentrations and is intended for applications where the wood won't touch soil directly, such as deck boards and framing. For garden edging that sits partially in soil, ground contact rated lumber is the appropriate choice to ensure proper protection and longevity.

What are safer alternatives to pressure treated lumber for gardens?

Cedar and redwood are popular natural alternatives that resist decay and insects without chemical treatment, lasting 15-20 years and 20-25 years respectively. Composite lumber made from wood fibers and resin offers 25-30 years of life with no chemical leaching concerns, while recycled plastic lumber can last 50+ years. For budget-conscious gardeners, untreated pine sealed with natural products like linseed oil provides a chemical-free option, though it requires more maintenance. (Get in-depth pros and cons  our lumber comparison post.)

How does pressure treated lumber compare to cedar or redwood for cost and longevity?

Pressure treated lumber offers excellent value at $5-8 for an 8-foot 2x4 with 10-15 years of life, while cedar costs $10-15 and lasts 15-20 years, and redwood runs $15-20 for 20-25 years. When calculated as cost-per-year of service, pressure treated lumber often provides the lowest annual cost despite its shorter lifespan. Cedar and redwood offer superior longevity and natural beauty but at significantly higher upfront costs, making pressure treated lumber ideal for budget-conscious projects where maximum longevity isn't the primary concern.

So, Now You Know👍🏼

Ready to get started with your pressure treated lumber garden edging project?

PTL offers the perfect solution for gardeners who want durable, attractive, and affordable edging that's easy to install and built to last. Whether you're creating flower beds, garden borders along paths, or landscape edging around your entire outdoor space, PTL provides a great choice that combines practical performance with natural beauty.

With proper safety precautions during installation and an understanding of the material's properties, you'll create garden edging that enhances your landscape for years to come.

Thanks for reading and good luck with your project!

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