Raised cedar beds

Hi all,

I was wondering if anyone has a suggestion on sealing the inside of a raised cedar bed. Of should I just leave it????

Keith in Colorado

Here's a shot of the raised beds I've been working on

I lined mine with a couple of layers of 4 or 6 mil poly.

You can sort of see it here too.

Stressbaby,

I had thought about plastic, but was worried that it would just hold mosture between the plastic and the wood. Then I thought that if I sealed it with just water seal it might add a few years to the life. I think that cedar is rated at ten years in damp locations. Did you put a layer of stone in the bottom of your beds?

Nice job by the way!

The more you can prevent direct contact between wood and soil, the longer it'll last, so plastic ought to help preserve its life. I'm not sure how much the Water Seal would do for something that's in direct contact with moist soil--those sort of things help with wood that gets rained on but then dries out, but I think being constantly in contact with moist soil, the Water Seal is going to wear out long before the 10 yrs that the cedar would naturally last on its own, so my thought is it won't significantly extend the life. Could be wrong though!

I built a small wooden boat and the hull below the waterline is sealed with epoxy resin. It's kind of a pain to work with but forms a watertight layer on the wood. I've used some of the leftover exopy to seal branches that I put in my terrarium/aquariums for decoration. Otherwise the branches just get moldy or fall apart. Since it's very glossy, you might use it just on the parts that contact the soil.

ecrane,

I wonder if the temp difference between the soil/wood would cause condensation at the plastic layer? I know I'm over thinking all this:-) But in ten years I'm going to be to old and grumpy to re-do it all!

Katlian,

Thanks, I'll look into epoxy. Though I'm a little concerned about have such strong chemicals at root.

Once the epoxy cures there is very little odor and I think the chemicals that are possibly emitted from it are very similar to the ones that come from plastic. I think epoxy is in the middle range when you compare how much VOC leaches from them. HDPE and LDPE are very low while PVC and polycarbonate are very high. The epoxy covered branch in my aquarium has not seemed to cause any harm to my fish, snails, or underwater plants.

I wouldn't worry about condensation, having plastic there isn't going to attract any additional moisture than what would be there in the first place, and having plastic between the wood and the soil is going to protect it from a lot of the moisture that it would be exposed to otherwise. The bulk of the moisture is going to be coming from your soil, so if you have plastic between the soil and the wood, you'll prevent a lot of moisture exposure to the wood and extend its life.

I also think the epoxy would be pretty safe--it's pretty inert once its cured, so I don't think you'd have to worry too much about things leaching into the soil (your Water Seal that you had mentioned earlier would probably leach more chemicals into the soil)

I'll do some research on both plastic and epoxy. I might t try an experiment in a corner with plastic and soil to see if i get condensation. I know if I bring my soda bottle out of the frig on a warm day I get condensation.

Thanks for all the help! What a great resource this place is.

This message was edited Jan 12, 2008 10:24 AM

Any amount of condensation you might get is still going to be WAY less than the amount of moisture in your soil that's going to be in contact with the wood if you don't put the plastic there. And the plastic doesn't create the condensation--if the humidity is right and the temperature differences between the bed and the air are right, condensation would happen regardless of the presence of plastic. The reason you notice condensation more on your plastic soda bottle (or other nonporous surfaces) is that they can't absorb the moisture so it sits in droplets on the surface rather than absorbing in as it would on a porous surface (like wood, fabric, etc).

ecrane,

These are good points, but the moist soil/cedar will dry out faster then the plastic/wood layer. Would you put a plastic tarp on your cedar deck for a winter? And wouldn't the the plastic act like a soda bottle separating materials of two different temps,. Also, I think it would be very hard to get all the plastic sealed, and would have moisture penetrate behind. Not to mention the inevitable tear from a shovel.

I'm really not trying to be pigheaded:-)

I'm not going to continue to argue with you on this, I'll just repeat one more time that your wood will come in contact with much less moisture if you have a plastic barrier between it and the soil than if you don't. Even if you do get condensation like you're worried about, the total amount of water that your wood is exposed to is going to be much less than if it's in direct contact with the soil. There's no way you can eliminate all moisture, no matter what you do the wood is going to come in contact with some moisture and is going to rot eventually. But direct contact with soil is the #1 factor that will make your wood rot faster, so if you can eliminate that, you're getting the most "bang for the buck" in extending the life of your wood. If you don't want to put plastic in there, there are certainly other ways you can do it, such as the epoxy that Katlian mentioned, I'd expect that would give you a similar extension of the wood's life.

I am so jealous of both of your raised beds. That is all I want this spring as I get older and don't want to work as hard to have a pretty cutting bed.

This is my thinking. I am 65 years old. I think that the females in my family don't live past their mid or late 70's so..................
If it only lasts me 10 years, so be it! Let my kids or the next owner worry about the raised beds (lol)

ecrane,
I think you are arguing with yourself. I'm just talking. If you wish not to have a conversation, then be quite.

gessiegail,

Check out the strawbale gardening forum. Looks like a great way to have a raised garden.

I didn't know they had a strawbale gardening forum. I can't wait to get there. Thanks so much! I hope it has to do with saving money (lol)

Fourks, in order for condensation to occur on the wood side, I would think that the plastic would have to be exposed to warmer, more humid air. It is true that at times the air in the GH is warmer than the cooler soil behind the plastic in the beds, but the plastic isn't ever really exposed to that air. It is behind the wood. Your cold soda will have condensation, but that won't replicate the situation in the plastic. I can tell you, having dug up enough soil and plowed in enough compost in these beds, that I have never seen any condensation behind the plastic.

Tears from the shovel aren't inevitable, but you have to be a little careful.

Stressbaby,

I'm going to give the 6 mil plastic a try. First I'll test it out in a corner of a bed. I guess there is no perfect solution, and if the beds need to be replaced in ten years, that still works out to a cost of about fifty dollars a year. With all the snow and cold weather, I have to much time on my hands. I'll post pictures of my finished beds.

Thanks for your time.

fourks, thanks so much for mentioning the strawbale gardening! I grow everything in containers and raised beds; can't wait to try the strawbales. It looks soooooo easy!

I looked at the strawbales and I have a veggie garden but don't want to plant my cutting garden down there so far! i want what you guys have and am going to show the pics to my brother.

Plus Dave has a good video about building raised beds. How tall are yours? I was thinking that perennials have roots of 12" so 12" high would be good enough. IS that true?

Yeah, I found the strawbale gardening interesting, but think I'll stick with good olé mother earth. Great idea for those that can't move the soil around any longer.

I got the cedar at home depot. I Think it ran about 1.30 a ln ft. My beds are on hard granite, so I had to go up two feet. I like to have deep beds, and many vegetables will grow roots that deep. If you have half way decent soil, then you can till up a foot before filling your bed. I'll have to check out Dave's video.

Good luck! The sun is getting higher each day!

Thanks for the tips. I don't have bad soil so I think I will just till down a foot, then add the good stuff and turn.

Good luck, gessiegail. If I tried that here, I'd have nothing but weeds. I know it's not supposed to happen, but I've had some of them grow up through 2 ft of soil. Got some industrial strength weeds around here.

Often you will have a weed party after tilling. It might be best to till the soil, and when the little buggers raise ther heads take a torch to them. Or clear plastic and cook them good.

Dunno, I've done all those things and still you would not believe the weeds here. It may be because we're in a fairly open, rural area here and there are just tons of weed seeds. It's why I started putting everything in containers. And even the containers get full of weeds if I'm not careful.

What we did at the garden to start it was to use round up and kill everything.........let it sit and when some weeds came back, pulled them up.

I had a big cutting open bed built when I lived elsewhere and he just took out 12" and replaced with good top soil with lots of bone meal and blood meal........I never had a weed.....in the 4 years I lived there. Thinking about asking him if he would bring down top soil to me here.

That doesn't work as well if you have a huge reservoir of weed seeds somewhere near you that can blow onto your property. Where I live (and it sounds like woofie's in a similar situation), I have a big huge field full of weeds behind my property, so no matter what I do, I'm always going to have an influx of new weed seeds coming in from back there. I have actually noticed a dramatic difference in the amount of weeding I have to do between my backyard and my front yard--the back yard butts up against the field, but the front yard has the house in between so not as many seeds make their way out there. I spend probably 10x as much time managing weeds in the back yard as I do in the front. Now if I wasn't so lazy about getting out there with the corn gluten, maybe I could cut down on the population some, but there are always going to be new weed seeds coming in no matter what I do.

ecrane3 I have the same weed problem. I'm surrounded by woods and meadows which fill the air with weed seeds all the time. Even soil I've purchased has come in with it's own share of weed seeds.

MollyD

Uh Oh....I may be headed for big weed problems with raised beds and I can't get a tractor in the raised beds like they do at the veggie garden and spray a weed prevention product.

Well, I hope gessiegail doesn't end up with our problem, but it sure is nice to know that I'm not the only one with this problem! I was thinking it was just because I was such a derelict about weeding! And until ecrane3 mentioned it, I hadn't really noticed that one side of my house doesn't have that problem--the side that doesn't get the wind. How 'bout that!?

Here's an updated finished picture of the beds. It was -27 degrees here last night. Might be a while before I get to plant:-(

fourks,

They look really nice! What did you use on your floors? Look like tiles.

MollyD

mollyD

I found some old mexican blocks on craigslist. They have voids in them like cinder blocks. So the whole floor drains to the otherside. Works great! you can see more detail on my other thread (dream greenhouse at 8600)

Love them fourks! Can't duplicate them but might use patio blocks in mine this year. I'm getting a HFGH and putting it in a new spot.

MollyD

Those beds are for a greenhouse!!!!!!! Amazing work you have done. I just noticed that you live in Colorado and need those for your short summers.

Yep! I'm going to be eating me some 87 dollar tomatoes this summer:-) Sometimes I dream of zone nine climate.

I've heard great things about the harbor freight greenhouse. Can't wait to see it go up!

I'm half looking forward to it and half dreading it since I know the extra work involved in making it strong. It's got to withstand really powerful winds here. A few days ago a windstorm brought winds of 75 mph for the better part of the morning followed by sustained winds of 40 mph and gust to 56 mph. So I have got to make sure it's secured to the ground and really braced . Every panel will have to be caulked and screwed so the winds don't rip them off. In mid winter that would be a calamity.

MollyD

Well, not sure how these attach,,but I poured 12"x36 deep footings every 6' around the perimeter and set stainless steel ties in the cement. attached with 6" lag bolts to 6x6 pressure treated landscape timbers. I have the same problem with wind, as I look off north to the continental divide. Also, I was able to place me GH so the house is a wind break from the North wind. 75 MPH winds are something to ponder.

Sadly I don't have the option of the house as windbreak since our predominant winds come out of the west. I was very proud of my little hoophouse since it withstood that storm without a single bit of damage.

I'm planning on doing a cinderblock foundation for the walls, two courses to get things leveled out.I'm going to run metal post into the corners through the cement and into the ground some 3'. That should stiffen things up quite a bit and secure it to the ground. The frame will be attached to these post. I was at Central Tractor and saw the ones I want to use at $25.00 each which isn't too bad. Some people have done cross bracing by adding extra metal across the frames. I'm wondering if I should do this on the diagonal to each wall as well.

MollyD