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All Things Garden,  Beginner Basics

7 Ways To Make Wood Garden Beds Last: Nontoxic Sealer & More

There are many benefits to gardening in raised beds or planter boxes: the improved ergonomics, clean appearance, ability to fill them with quality soil and compost, and it’s easier to block out pests. I love raised beds! Yet one of the few drawbacks is that they don’t last forever (and, they aren’t exactly cheap). So, protect your precious investment and follow these 7 ways to make wood garden beds last longer! We’ll talk about how to seal garden beds, lumber choices, drainage and more.

I’ll admit, we never sealed our garden beds in the past. They’re made from super durable heart redwood, after all! However, once we moved to our new homestead and began building our “forever garden” (and felt the rude awakening of not being in our 20’s anymore during the laborious process) I thought to myself: I want to make these garden beds last a LONG as physically possible. 

In fact, we seriously contemplated getting some awesome Birdie’s galvanized metal raised bed kits instead. Those things should last forever! (And you can save 5% with code “deannacat3”). But in the end, my love for the look of rustic wood won that battle, so here we are: we just finished building 19 new redwood garden beds, sealed and siliconed this time. Do it once, and do it right.

After reading these tips, pop over and follow our step-by-step guide on building wood raised garden beds!

A large gravel garden area that is lined with large rocks on the border with many wood raised garden beds evenly spaced throughout the area. There are oak trees in the foreground and background as well. The beds are full of soil but have yet to have anything planted inside.
Our brand new garden. I can’t wait to see her planted and full of life!


1) Choose wood that is naturally long-lasting 

One of the best ways to extend the life of raised garden beds is to use quality, long-lasting lumber right from the start. Cedar and redwood are two excellent choices, as they are both very dense and durable. Thanks to their high tannin content, both cedar and redwood are naturally resistant to rot, mold, and insects – including termites. Heart redwood lumber (what we use to build our raised beds) is even more indestructible than common redwood boards. 

Garden beds built from untreated cedar or heart redwood can last well over a decade on their own – likely much longer, depending on the climate and other conditions. The 7-year old untreated heart redwood beds in our old garden are still in excellent condition. I’ve also heard stories of friends’ redwood beds lasting well over 20 years! Then, if you follow the other ways to make garden beds last longer as described below, you can extend their life by several years more.

In comparison, garden beds made of softer woods like Douglas fir or pine can rot out and decay within just a few years. Don’t be tempted to use pressure treated lumber (usually treated pine) to make garden beds last longer either! In addition to containing undesirable chemicals not ideal for organic gardening, the lifespan of treated wood is less than cedar or redwood anyway! Especially when it is in constant contact with soil and moisture – as it will be in your garden.

Three garden beds of varying ages and color are sitting atop gravel hardscape. Two of the older beds are planted out with bok choy and various greens. The smallest and newest garden bed has just been topped off with soil. There are various salvia, cacti, fruit trees, and other perennials in the background.
Heart redwood garden beds at various ages in our old garden. The big bed in back (most gray) is about 6 years old in the photo. While the color has faded with age, it is still perfectly structurally sound. The bed in the foreground is 1-2 years old, and the smallest one to the left was brand new.

2) Use wide planks and thick boards

Choosing wide lumber planks is another excellent way to extend the life of wood garden beds. For example, a raised bed constructed out of 2×6” boards will last longer than one made from 2×4”s. Eight, ten, or twelve-inch wide boards are even better! Raised beds are most susceptible to rot in the seams between the boards, where moisture collects and air is scarce. By using wider planks (and thereby reducing the number of seams in the bed overall) it is reducing surface area and places for water intrusion. 

The same idea applies to board thickness. While 1-inch thick boards are often more affordable (such as cedar fence boards, which are actually only ¾” thick), the raised bed will not last as long as one constructed with 2-inch thick boards. Plus, thinner boards are more likely to bow or even crack over time under the pressure of heavy wet soil pushing against them. Last but not least, thick 4×4” corner supports will last far longer than using 2×4’s or other smaller wood in the corners.

A concrete patio is being used to construct garden beds. There are pieces of 2x6 boards and 4x4 boards as well. One bed is laying on its side, fully constructed. The patio is lined with older garden beds that are filled with various vegetables. Two chickens stand in the yard beyond, visible between two of the beds that create a gate. Using cedar or redwood help make garden beds last longer.
We make our heart redwood raised beds with 4×4 corners and 2×6″ boards. These beds were extra tall, but now we usually make them 3 boards high. We haven’t been able to find 8″, 10″, or 12″ tall boards here easily – but we’d use those if we could!

3) Seal wood garden beds (with non-toxic sealer)

Sealing wood garden beds can help extend their lifespan many years beyond unsealed wood. Applying a sealer will protect the wood from moisture intrusion, mold, and decay. However, you don’t want to use just any wood sealer on your garden beds! Many sealants and stains contain toxic chemicals – stuff you don’t want around your healthy homegrown food and soil.

We recently used this nontoxic wood sealer on our new redwood garden beds. If you know me, then you know I do my homework before choosing materials to use in our home and garden! This particular product is food-safe, made in the US, won’t leach, has no VOCs, carcinogens or endocrine-disrupting compounds, and is nontoxic to wildlife. Plus, it gets great reviews!

We ended up applying 3 coats of Garden Seal to the inside of our beds (where rot is most likely to occur) and had enough left over to do just one coat on the exterior. It goes on milky white, soaks into the wood well, and dries clear with a slightly satin finish. However, the third coat inside the beds did leave a bit of a visible residue, so one or two coats for the exterior would be best. Be sure your wood is totally dry before application.

Hope’s Natural Tung oil is another nontoxic option to seal garden beds, though I’ve heard it’s best to reapply it annually – which is why we chose the other sealer. This would be a good option to seal the exterior of garden beds where routine application is possible. 

A 5 gallon bucket of Garden-Seal sits inside a raised bed. A paint roller is upside down, leaning against the bucket.
The nontoxic wood sealer we used on our new raised beds. We got a 5-gallon bucket since we were sealing 16 4×8′ beds (plus a few smaller ones). After applying three coats to the interior only, we went through about 3/4 of the bucket. So, the smaller one-gallon option would cover most home garden projects.
DeannaCat is using a paint roller to apply the sealant to the inside of the garden beds.
Applying the sealer with a paint roller. If you plan to seal both (all) sides of your wood, it is MUCH easier to seal the boards before assembling your raised beds. We didn’t decide to seal our beds until after they were already built (and only did the insides at first), so we applied the sealer to the already-assembled beds.
The inside of a garden bed is shown, half of the bed has had an application of sealant where the other side is still natural. The sealed side is slightly darker than the unsealed side. A paint tray and roller sit in the foreground with some milky colored sealant in the bottom. Seal beds to make garden beds last longer.
Unsealed redwood on the left, and after one coat of sealer on the right.
5 wood raised garden beds, full of plants and with gravel around them. In front of the beds sits a 5 gallon bucket of nontoxic wood sealer and a paint roller. Three of the beds are sealed and appear darker in color with the knots in the wood showing through more, where the two unsealed beds are lighter tan.
We were in a bit of rush to get our new beds filled and ready for spring, so we initially only sealed the insides. Then once things settled down, I went back and applied one coat of sealer to the outside of the beds too. You can see how much it makes the color and wood grain pop (sealed on the top/right, unsealed on the left).

4) Seal garden bed seams

In addition to sealing the wood itself, consider sealing the gaps between the boards. Again, wood garden beds are most prone to decay in their deepest nooks and crannies, including the corners and horizontal seams between the wood. When building our newest raised garden beds, we applied clear silicone to all the seams – which is waterproof, inert, and nontoxic once it dries. My friend Steve has been professionally installing and maintaining organic gardens for over 25 years, and he claims that this single step can extend the life of garden beds by 5 to 10 years!

We used a class 50 premium exterior silicone (or this similar option) to seal our garden beds along the inside seams only. Class 50 silicone is far more durable, flexible, and resistant to temperature swings than lower-rated classes. This is important since garden beds are exposed to varying temperatures, and the wood constantly swells and shrinks with moisture.

Use silicone to seal garden bed seams just like you would caulk. First, squeeze it deep, thick, and evenly into the cracks. Then while it is still wet, tuck your finger inside a paper towel and gently smooth it out – removing gaps, air bubbles, and excess. Pay special attention to sealing your corner supports! I also added a dab to any open knots, holes or cracks in the bed interior.

DeannaCat using a caulking gun with a  tube of silicone inside to add silicone to the seams of the raised beds.
Applying silicone to all the board seams with a caulking gun. For reference, I needed about one 10 oz tube of silicone to seal each garden bed measuring 4 x 8’ and 3 boards tall.
DeannaCat is using her finger and a piece of paper towel to smooth out the silicone that was applied to the seams to help against water intrusion.
Squeezed a good amount in there, and then smoothed it over with a paper towel/finger.
The corner of the inside of a raised bed is shown, the seams in between the 4x4 and 2x6 boards are sealed with sealant.
The final result. All sealed and waterproof!

5) Reduce wood-to-earth contact 

Clearly, your garden beds are going to be full of soil – so a certain amount of “wood-to-earth” contact is a given! Yet beyond their seams, wood garden beds are also quite susceptible to decaying along the bottom perimeter. There, they’re essentially sitting in constant moisture. So, another clever way to make garden beds last longer is to avoid setting the wood right on the ground. 

Our raised garden beds are perched on top of a couple inches of well-draining gravel. Because we have a nasty gopher problem, we also have hardware cloth and landscape fabric (permeable to water) below our beds. However, that isn’t to say you can’t have the bottom center area of your beds open to the native soil below if you prefer! I’m just talking about the wood itself. 

My pro garden friend Steve installs all his raised garden beds on top of a gravel border, similar to a french drain. To do so, he digs a small trench (about 6 inches wide and deep) and fills it with fast-drying ¾” leach rock. Then the perimeter of the wood garden bed frame sits on top.

Three redwood garden planters lined up one after the next with pathways between. They are sitting atop gravel which will help with drainage to wick away moisture.
Our raised beds are set on top of gravel, with hardware cloth in the middle to block gophers. Yet you could leave the middle of your raised bed open to the native soil below and only create a “tunnel” of gravel around the perimeter for the wood to rest on.

6) Shou Sugi Ban garden beds

Shou Sugi Ban is a Japanese wood preservation technique that involves burning or charring wood surfaces. The charring process essentially seals the wood, making the wood more resistant to water and insect damage. Shou Sugi Ban garden beds should last several years longer (or more) than untreated wood of the same species. 

To char wood garden beds Shou Sugi Ban style, most folks use a blow torch or propane weed torch. We’ve never done this ourselves, but I’ve heard one drawback is that it does take a lot of fuel and effort. Experts also say it’s important to not burn it too heavily, since deep burns can actually make the wood more susceptible to decay and reduce structural integrity.

This article explains more of the process. This YouTuber also shows his Shou Sugi Ban raised beds here – along with an update showing the inside of his bed 1.5 years after use.

Three wood garden planters sitting on top of bare dirt. The insides and bottom of the planters have be slightly burnt using the Shou Sugi Ban method.
Just as we chose to seal only the inside of our new raised garden beds, this person applied the Shou Sugi Ban method to only the inside and bottom perimeter of their beds – the most vulnerable places. Image via Reddit.

7) Promote good drainage

Good drainage is key when growing in raised beds. Plants prefer fluffy, moist, well-draining soil with plenty of air pockets for exploring roots and beneficial microbes. They don’t like soggy, heavy, compact soil – and neither does your wood! Heavy soils that hold in too much moisture can increase the likelihood of wood decay. On the other hand, raised beds tend to dry out more quickly than in-ground gardens. It can be tricky to achieve the perfect balance! 

Fill raised garden beds with soil that is made for containers or raised planter boxes. This article discusses how we create our own soil blend with bulk soil, compost, and an “aeration” component. Aeration additives include perlite, pumice, sand, peat moss, coco coir, rice hulls, or our favorite: ⅜” lava rock. It promotes that ideal blend of moisture retention and good drainage.

Furthermore, never seal off the bottom of your raised beds with impermeable material, such as a plastic lining. You want your beds to drain freely! I also do not recommend lining the wood walls with landscape fabric, even “permeable” and breathable ones. The fabric will hold in extra moisture right against the wood.

Elevated garden beds or those installed on top of hard surfaces (e.g on a patio, driveway or deck) should have plenty of drainage holes in the bottom – just like pots. For instance, we drill at least half a dozen ½” to ¾” holes in the bottom of our wood wine barrel planters.

Aaron and Deanna taking a selfie standing in front of their new garden area that is in the process of being created.
Our newest garden beds – all sealed, siliconed, and being filled with fluffy, rich, well-draining soil. These babies should last well over 20 years… hopefully 30+!

And that is how to make wood raised garden beds last as long as possible!

All in all, raised garden beds are a fantastic way to grow food, flowers, herbs and more. I love their sleek look, and for us, the ability to block gophers from getting inside. I hope you picked up a few new tips to help extend the life of your beautiful raised beds today. If you found this information to be valuable, please spread the love by pinning or sharing this post. We wish you the best of luck in building and preparing your beds – with years of bountiful harvests to come!

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    • Aaron (Mr. DeannaCat)

      Hi Monica, we used half 3/8th inch gold granite and half 3/8th inch green rock. When it comes to gravel and hardscaping, it really depends on what quarries if any are nearby your location as that directly correlates to what rock your local bulk landscape supply company may have. Hope that helps and reach out with any other questions.

  • Kate

    Hi, Love the info on making raised bed. Couple questions.
    *Are the metal bars in the inside center of the boxes for adding a wood brace to keep bed from bowing?

    * We are taking down our cedar deck we didn’t use and I want to resuse the lumber. I want to put some of the raised beds where the deck was which already has white landscape rock with plantic under that. Being that I live in MO with terrible clay I’m thinking I should remove the plastic and and add more but smaller gravel and maybe sand to level boxes and better drainage? Did you put landscape fabric down under the rock in the walkway between boxes?

    * The deck was stained about 7 yrs ago so I’m thinking I just need to cut off any rot and just sand down the boards and restaining and seal?

    * I have have 6 Raspberry bushes, 6 Blueberry bushes, 6 Blackberry bushes, and 4 Rhubarb planted in used black landscape pots. How big would you recommend I go with the boxes? I’m thinking at least 15″ deep and 2′ wide and 3 to 4′ per box which would give me enough room for 2 plants per box. The deck wood was 2×6 but have shrunk a bit so I will probably have to do some adjusting/ cutting. No worries power tools are my friends.

    Thank you for any and all suggestions!

    • Aaron (Mr. DeannaCat)

      Hi Kate,
      – Yes the metal brace is just extra reinforcement to keep the boards in line with each other and hopefully prevent bowing.
      – We do have landscape fabric underneath our gravel, you could add more gravel so your beds have a bit more to sit on which should help with drainage, sand may not be necessary as you can build up more gravel along areas that you need to raise.
      – Sounds good on cutting out rotten boards and re-sanding.
      – 2×4 foot beds sounds like they should work great for you! We had a few of them at the old property and they worked quite well.
      Looks like you have a good grasp on what you want to do and will be plenty busy with the project, best of luck transforming your space!

    • Robert C Zornes

      While I use building stone rather than wood for my raised beds, this is very good advice. One thing I would suggest is that rather than using a paper towel on the “caulking”, I’d use a disposal silicone or “rubber” glove.

  • Vitaly

    Thank you for such a detailed article!
    I just bought a raised bed made of untreated cedar to replace an old one that is breaking down after at least 9 years of use.
    It has caps over the posts, they should help keep the moisture out.
    What do you think about putting continuous line of bricks, as an alternative to gravel, under perimeter of a raised bed – to keep it elevated and relatively safe from persistent ground moisture?

    • Aaron (Mr. DeannaCat)

      Hi Vitaly, bricks will likely do a better job at remediating persistent moisture than if the bed was dug into the earth itself, however the bricks will still likely absorb some moisture as they are porous. I would also be sure that the bricks are firmly in place, maybe even using a construction adhesive to stick them together, also the bricks may shift with time as the ground shifts over the years. The idea of using gravel or float rock is that the moisture will drain through the gravel and not held within the rocks themselves. We did make a concrete paver foundation for our greenhouse on our old property and you may want to check out the article to get a few ideas if you want to proceed with your plan. Hope that helps and good luck setting up your new garden bed!

    • Aaron (Mr. DeannaCat)

      Hi Leah, those are PVC risers that we connected to a main PVC system we installed to irrigate our raised beds.

      • Melissa

        Hi, If you are concerned with toxicity, then why are you watering your organic garden with PVC pipes? Isn’t PVC full of toxins? Is there any non-toxic way to irrigate a garden. That’s my biggest question! So far I’ve only found one non-toxic soaker hose on the market and no drip irrigation system. What’s the point of caring about non toxic and organic when your water is coming through toxic plastic tubes!!??

        • DeannaCat

          Hi Melissa, Schedule 40 and Schedule 80 PVC is actually approved/made specifically for drinking water systems (stable, no leaching, etc). I used to work as an Environmental Health Specialist (the senior water system specialist to be precise) for the county before I quit to work on our site full time, and believe it or not, PVC is the most common material used for drinking water systems for homes. Same with the drinking water storage tanks… Furthermore, quality soil amended with organic matter such as compost and worm castings does a phenomenal job at remediating toxins from soil (that’s been proven in scientific studies), so that helps put our mind at ease. Drip tape (what we use) is nice because no water sits in them. They deflate/de-pressurized after the water is off, so it’s not like the water is sitting in constant contact with them, especially not sitting there getting hot in the sun, which is where the biggest leaching concern would be. If you’re most comfortable with the BPA-free soaker hoses that we used to use, then that is a good option too, though no option is perfect. We’re just doing our best. With such a large garden and climate that doesn’t rain 75% of the year, automated drip is the way to go.

  • Mags

    Quick question! Would sealing the cedar with the one you reccomend actually negate the peat control qualitiies of cedar? Trying to make my beds last as long as possible, but don’t want to take away the prst control!

    • Aaron (Mr. DeannaCat)

      Hi Mags, are termites the specific pest you were trying to keep away? If so, sealing the cedar will seal in the phenols that repel pests but I would imagine if the termites start eating the wood, once they get past the layer of sealer, the phenols would be active and should still do their part to repel the pest. You just have to determine what is going to be the bigger issue for your raised beds with time, is it the moist soil and water intrusion that will eventually rot the beds in time or are the termites the bigger issue? It may depend on your specific location, rainfall amounts, and pest issues. Hope that helps and good luck!

  • Tara

    Hi there!
    Wondering if you would suggest these same sealing methods for wine/whisky barrels or if that might not be necessary.
    Thanks for sharing your epic homesteading knowledge! I have learned so much!!

    • Aaron (Mr. DeannaCat)

      Hi Tara, you could try it but the sealer might not take as well to the wood as it has had wine or whiskey touching it for who knows how many years. Wine barrels left unfinished still last for a number of years, we have yet to throw one away in the last 8 or so years of use. Hope that helps and have fun growing!

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