Sealing Planter boxes

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Forum topic by xhandal posted 04-20-2009 05:05 PM 38576 views 1 time favorited 10 replies Add to Favorites Watch
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9 posts in 3518 days

04-20-2009 05:05 PM

Topic tags/keywords: question

Hey all.

I work in a feed store/fertilzer plant and we have a pile of odd sized pallets laying around that we just give away or burn. I came up with an idea to take them and make them into planter boxes.

I want to know, if I seal or stain the boxes, would it still be wise to treat them with a Thompsons sealer additionally or would the stain/seal be enough to help the wood weather well?


-- No Farmers = No Food

10 replies so far

View Vicki's profile


1099 posts in 3339 days

#1 posted 04-21-2009 05:58 PM

Just my 2 cents from having made many outdoor planters. Most all of mine the joints seperated, the boards cupped, etc. I used PT lumber for my planters and stained them. I plan to paint any future planters in the hopes that it will seal the wood better and protect the planters from the elemants. The stained ones look nice the first season, but fade quickly.

-- Vicki on the Eastern Shore of MD

View Kindlingmaker's profile


2656 posts in 3521 days

#2 posted 04-21-2009 08:29 PM

Out door planters either have to have a liner or be of the right wood and there are very few of those. If wood is sealed on all sides it will hold in the moisture and cause rot. Its like a fence post, they look very worn and rustic after a few years but will stand for many decades. If the fence posts are sealed with a paint then they will rot and fall, no real way the keep all the moisture out and that which gets in will stay. I think if I were going to make a planter with anything except redwood with an outside metal band, I would use green lumber and keep it moist after the box is built. ...just a thought.

-- Never board, always knotty, lots of growth rings

View Jeremy's profile


74 posts in 3325 days

#3 posted 04-22-2009 12:57 AM

Here’s my two cents. I too have made planter boxes, many in fact and have grown to like Helsmans (Spelling)Spar Urethan. It comes in green can and I bought it at HD. Its a little pricey at 15 bucks a quart. It is an alternative to Spar Varnish which is what they use on the haul of wood boats. Spar Varnish would be best but is a little hard to come by depending on what state you live it because it is a very harmful chemical. So, I read. I couldn’t get it here in New York and couldn’t get on the net because company’s won’t ship it here either. But, like I said that Helsman spar Urethan is good stuff! I hope to get 10 years out of boxes as I know it won’t protect forever. Maybe more if I empty them out every year and give them another coat or somthing, but seriously, who has time for that? Besides, in 10 years or so when they break down, I’ll have another project to work on. I would suggest using pine or some other wood that will do better outside. DON’T USE POPLAR! I learned the hard way! Soaked up the water and was a mess. Stupid! Good luck! I hope that helped!

-- Jeremy, Rochester, NY

View Julian's profile


880 posts in 3520 days

#4 posted 04-27-2009 12:09 AM

Thompsons is crap, don’t waste your money. The wood you choose should be one that is naturally rot resistant. Redwood is great, as well as white oak, and cedar. Pressure treated lumber is junk these days, as it’s all young trees that it’s harvested from. Once you have a decent wood then you need to finish it with spar varnish or spar urethane, or let it weather naturally, which it will do eventually anyways.

-- Julian, Park Forest, IL

View juniorjock's profile


1930 posts in 3760 days

#5 posted 04-27-2009 02:12 AM

I agree with Julian. Thompsons is over-priced and just doesn’t work. The right lumber will do the trick. But for even better results, use some kind of liner.

View RalphB's profile


25 posts in 3360 days

#6 posted 05-09-2009 04:39 PM

I think what you are seeing from these comments is that there are are two sides to this issue: the inside and the outside! Here’s some thoughts:
INSIDE: From my own experience if you want a planter to last you need to have a liner on the inside. Even redwood (much of what nowadays is pretty poor quality) will not last forever with moist soil against it – rot is inevitable. The simplest liner is heavy gauge plastic like “visqueen”, you can even double or triple layer. But it’s hard to make “joints” that won’t leak and then the wood rot sets in. Rubber-like sheeting used for foundations or roofing are outstanding, but pricey – and they can be pierced by trowels or weeding tools. Sheet metal (Galvanized steel or aluminum) is to my way of thinking the best of all. (I prefer galvanized steel) Sheet metals are relatively cheap and easy to work with and a little simple bending and soldering or caulking/gluing can make a leak free container of almost any dimensions. No matter which way you go for a liner, make sure to allow for drainage (1 or more holes). I like to use some plastic pipe to carry the water well clear of the wood.

OUTSIDE: I think that the choice of wood makes a huge difference here. Some woods will hold a finish better than others. Also, some woods like redwood, cedar, locust, etc are known for excellent outdoor resistance. I think that there are very few, if any, clear finishes that will last. Remember, even boats with extremely high quality varnishes require constant care. Paints and penetrating stains (and some “oils”) last longer in my experience. But the lowest maintenence is if you let the wood oxidize to its own natural weathered state. Once the outer layer is well oxidized it actually serves somewhat as a sealer. But this is really only practical for those woods that have inherent resistance. Lastly, what the outside looks like is of course a matter of taste, too. So if you need a pristine, crisp look, or you want good control of the color – paint or solid body stain it. For a more rugged or natural look – stain or weathered is the way to go.

Just my opinion – free, and worth every penny of it!

View VegasRick's profile


2 posts in 2259 days

#7 posted 03-14-2012 03:50 PM

Hello all – just came across this – I painted my pallet planter with latex fence stain and then sealed the inside with liquid rubber… Spent a lot time looking for a rubber type sealant that was plant safe… and one that would stand up to the elements… It worked for me!

View landartist's profile


2 posts in 2256 days

#8 posted 03-17-2012 09:43 PM

VegasRick, great video.

Can you tell me the brand name of the plant safe waterproof coating you used? Also, what is the white reinforcing fabric you used?

I could not quite tell what you did with the weed barrier material that was designed to let the planter drain but keep the soil inside.



View VegasRick's profile


2 posts in 2259 days

#9 posted 03-18-2012 04:11 PM


I used Rubberizeit! – it’s liquid rubber that is non-toxic – I got the white reinforcement cloth from them too.

When I built the planter I sorted the wood that came off the pallets – used the best pieces for the sides, front/back – some of the other pieces weren’t so visually appealing – so I used those for the bottom.. This created gaps between the rungs – so I used the weed barrier on the bottom – only painting the rubber on where the wood is – leaving just the mesh to go over the gaps… this way there would be drainage… and the rubber held the weed barrier in place.. am I making any sense at all?

Thanks for the complement on the video!

I hope this helps!


View landartist's profile


2 posts in 2256 days

#10 posted 03-19-2012 02:30 AM

That reply was very helpful and I understood everything you said. I wish you success with other projects so you will have other things to share with us.


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