Raised Bed...part 2

[illinifans]

Yeah I never thought about the glue. I may make a couple of the beds 12" and two of them taller for shorter crops.

[Worth1]

Originally Posted by illinifans

Okay I'm new to tomatoville and this is my first post. We took down our 24 foot above ground swimming pool and part of our deck last summer and I am planning to convert that area to 4 large raised garden beds. I know it might sound crazy, but I'd like to build them 4'x20' and make them 24-30 inches high (getting to old to bend over so much). Has anyone ever tried to build a box say 12 inches high and then put dirt on top of that? My plan is to strategically place cinder blocks or framed wooden boxes on the bottom of the beds and place 4x8 sheets of plywood on top of them. Then fill at least 12 inches of cardboard, leaves, mulch and dirt on top of the plywood. I know the plywood will eventually break down and I'd have to add more dirt in subsequent years but I hope to get maybe 5 years out of this methodology. Any thoughts or ideas? Is there a better way to build up the beds?

I'm lost.

Worth

[illinifans]

Sorry Worth. Basically the dirt in the tall beds will sit at least 12 inches off the ground on top of raised plywood. That way I don't have to fill it with so much dirt but the beds will be almost waist high when it's finished.

[jmsieglaff]

I don't think your method would work. So you suggest 24-30" tall beds with the plywood 12" off the ground. That leaves 12-18" of soil (and eventually copious amounts of water from summer thunderstorms) on sheets of plywood. The plywood would bend, warp, and eventually break if not break outright I'd think. So even if you plan it being 12" off the ground, the bending and warping of the wood would leave you much closer to filling the entire bed with soil than what you'd plan for. Additionally, if the wood didn't break immediately but toward the sides after a while you'd have suddenly sinking regions of garden.

If it is important to have higher beds you might want to look into building sturdy raised garden beds or garden 'tables' 4'x4' or maybe 4'x8' out of stuff like cedar. The problem with that is the expense--but if you did a couple at a time maybe it would be doable.

Browsing through commercially available planters may give you some ideas (http://www.gardeners.com/buy/gardeni...-garden-boxes/)

[illinifans]

The cinder blocks would be placed under the center of each sheet of plywood as well as 4-6 around the perimeter of each sheet. My plan is also to place 4x4s in each corner dug into the ground a few inches. Plywood over all that and 2"x12" fir sides. I looked into cedar and its just too expensive. I figure I can replace the boards 3 or 4 times for the same cost. But I can see your point especially with regards to the heavy water even though there would be drain holes. Might be worth a try and like I said if it all collapses in a few years, I would just add more dirt.

[FarmerShawn]

Instead of the plywood, why not just use one inch rough cut boards? You wouldn't have to worry about glue, drainage could be part of the construction by spacing the boards, and, at least around here, the cost would be much less. Boards would last at least as long as the plywood, I'd think.

[Steelcurtain67]

Just a thought. I wanted to use high raised beds myself (I am in my 70s) so I built them 4x8x24" and had to find some cheap stuff to fill them. I found out, quite accidentally that my town had free leaves in huge piles at their recycle center. They didn't have anything about them on their website and most of the people working for them did not seem to know. Leaves make some of the very best compost as they have all the minerals that the tree pulls up from the ground and they contain a lot of lignin so they rot fairly slowly. If any of the towns around you collect leaves or lawn waste they probably have a place they are putting them. You do have to be careful about grass cuttings as they may have herbicide on them, but you can ask at any large institutions in your neighborhood like schools, university, hospitals with grounds, etc to see if they are using herbicides.

Good luck.

[jmsieglaff]

Originally Posted by FarmerShawn

Instead of the plywood, why not just use one inch rough cut boards? You wouldn't have to worry about glue, drainage could be part of the construction by spacing the boards, and, at least around here, the cost would be much less. Boards would last at least as long as the plywood, I'd think.

I like that idea a lot. Drainage and roots will go between the boards (placed narrow dimension facing up). It buys time for having to add a ton of soil. Untreated pine would decay without worry of chemicals. You could even use 2x10s or whatever height you want.

[drew51]

I myself switched to treated lumber, as here all they put in it is copper. I have blueberries, blackberries, raspberries, peach, plum, and cherry trees I spray once a year with a super strong copper. It's a great fungicide. Plus copper is an essential element for plant growth. Although plenty is in soil naturally copper toxicity is a worry, but not for me, for my plants.
So I limit use to one spray a year.
So as my raised beds decay I will be replacing wood with treated wood. Currently it is untreated. I also seal them with a latex stain. Latex is fairly safe too, I paint the trunks of all my trees with a latex paint to prevent sunburn, and prevent borers. I add plaster and sometimes an insecticide for borers. It's tough to grow fruit trees, but picking that fresh peach off my own tree is wonderful. You just can't buy peaches that good. I grafted a number of varities unto my trees, so I have many peaches, and plums all summer.Franken trees! I like to have 3 or 4 cultivars per tree. You can graft plums on peaches, pretty cool!

[Worth1]

If I were to do this I would use 3/4 plywood exterior non treated sheathing.
I would make them 3X8 I have some 4 foot wide beds and they are a real pain to get to the middle.
Take the 1 foot scrap you have left over and rip it down to 3-1/2 inch strips.
You will have 3 strips and one narrow scrap piece.
Build your frame first with the 2X12X8 lumber and then measure the dimensions on the inside of the box.
These dimensions will be a little smaller than what you were going for but you want to make sure everything is nice and square.
Once you have done this you will know how wide to make the bottom piece out of plywood.

What ever that inside dimension is rip the plywood 1/8 inch smaller all the way around.
Take the strips you have and glue and screw them to the bottom of the frame flat ways with Tight Bond lll wood glue.
These are called cleats.
Then put the sheet of 3/4 plywood on top of these inside the frame.
The reason to cut the sheets 1/8 smaller is so you will have room to set the sheet in the frame.
This will leave about 1/16 inch gap all the way around.

Before you set the plywood in the frame make sure you put the glue all the way around on the edge of the cleats you installed earlier.
Use a few 1-1/2 screws to hold it down angleing the screws into the 2X12's not the plywood cleats.

Then flip the box/bed upside down.
Measure the inside of the box and cut 4 2x4's the correct length and screw and glue them in edge ways under the bed.
Then screw in from the top through the plywood later. make sure they fit tight and do not screw from the outside into the ends of the 2X4.
Then cut 4 2X4's the length of the outside width of the planter.
Screw and glue these flat ways to the 2X4's you installed before and now into the 2X12 lumber.
Don't forget to mark where this are before you flip it back over again so you will know where to put the screws.
(2x4 lumber is really 3-1/2 wide this is the reason for cutting the cleats 3-1/2 wide).
You now have really strong T shaped supports to hold you soil in.
No worries about sagging.
Now you have a planter but you still aren't through yet.
Use a hole saw and make some drain holes in the bottom of the planter.
Treat the inside of the planter box with a protective sealant and let it dry.
Put a 2 layer sheet of vapor barrier inside the box and along the sides.
You can use an adhesive to make it stick.
take a knife and cut an X where the holes are and push the plastic vapor barrier down through the hole.
Paint or stain the outside your favorite color and enjoy.
No need to worry about glue leaching into you soil.

An alternate method would be to also install 4X4's in each corner and 2 in the middle on the sides. doing this inside the planter.
To do this you would have to notch the plywood.
Doing this would allow you to have them as tall as you wanted.
It would eliminate any need for cinder blocks.
And you could set the 4X4s in special made cinder blocks so they wouldn't be on the ground.

I can promise if this is done correctly you wont have to worry about building them again for many years to come.

I also want to add if you dont have a really easy way the rip the plywood you can get the store Like (HD or Lowes) for a small fee.
3/4 plywood can be very heavy and you want to make clean accurate cuts.


These are the blocks I was talking about.




Worth

[illinifans]

There are a lot of great ideas here. Luckily, I still have a couple of months to look them over and modify my plans as needed before I start constructing.