I don't have suggestions for the grid, but am curious why you plan on stacking 2x8s. 16" high is overkill for just about everything. You could lower your project cost 50% by going with a single level of 2x8s.

Also, for longevity I would use angle brackets rather than screwing wood to wood.

The squares will be built on very sandy soil.

I'm not sure what you mean by adding another 2x8 or 1x8 to the soil for the potatoes. Do you mean to have the square 2 high?

I'm really thinking that I should pare back to one level after considering what you wrote.

I'm having trouble envisioning the corners with the L brackets. If they don't overlap, don't you need a 45° angle?

Thanks for taking the time to write.

I do agree on the height issue doubling the costs. Also if you are placing the frames on top of the ground (as I did with mine), you will find the frame will shade the plants near the edge (early on) until the plants grow more. Unless you plan to fill the frames with MORE soil, adding to the cost.

The fact is, should the need arise, it is easy to put another frame on top. I flipped ALL my frames over this year hoping to keep the wood from rotting where it contacts the soil.

As far as the corner brackets, I have done mine both ways and have not noticed any longevity problems, either way. I say use whatever you have on hand to keep the expense of gardening affordable.

Spare the 2nd story frame, send the extra money to Gumby Damit.

My 2 cents...
Gumby_CT

I don't think that angle brackets and L brackets are the same thing. In any case, angle brackets are more suitable for the boxes if you're using wood as old as the wood from which I built mine. Simply screwing them together, the wood around the screws split and loosened and the screws came out completely.
To use the angle bracket, put the bracket completely flush with one of the boards. Then put the second side board flush with the angle bracket and the first board. So yes, they do overlap.
As far as the grids go, is there any kind of basket weaving thatch material that you could tack into the sides of the boxes?

Yea ok, I think I pre-drilled mine to avoid the splitting.

---I'm not sure what you mean by adding another 2x8 or 1x8 to the soil for the potatoes. Do you mean to have the square 2 high?---

Yes, but perhaps not in the way you are thinking. When potatos are grown at home the usual method is to plant them and then cover with a few inches of soil. As they grow, keep adding soil to cover more. At the end you have a hill of soil filled with potatos.

However, instead of building your bed(s) with stacked 2x8s all the way around, just make them single level 2x8s which is more than adequate for almost everything. That these will be on sandy soil is super for drainage too. You could do 6" if you wanted with no problems.

OK, so you start with your 2x8 bed and plant potatos. They grow and now you want to mound soil. Here is where you take a 1x8 frame and set it inside the 2x8 bed right on top of the soil. This way you can add soil to this portable frame to keep the taters covered and don't have to make the entire bed double stacked 2x8s. Just trying to keep the cost down and functionality up. 1x8s would be more than adequate for this purpose and a lot lighter too.

-- I'm really thinking that I should pare back to one level after considering what you wrote. --

Save the money and spend it on something else. A 16" depth in a raised bed is really unnecessary, even less necessary with a sandy soil underneath.

-- I'm having trouble envisioning the corners with the L brackets. If they don't overlap, don't you need a 45° angle? --

I was confused by 'overlap'. Yes, they will overlap, no you do not require a 45 degree cut.

Let's say you wanted a bed 8' long and 4' wide on the interior. You would get 2 8' long 2x8s. You would then use 2 4'3" 2x8s as the 'end caps'. Since a 2x8 is 1-1/2 inches thick, you need the extra 3 inches for overlap.

Why do you want the angle brackets? Imagine all the weight of the soil, particularly when wet or when it freezes. It pushes against the boards of the frame. What is there to prevent the frame coming apart? If it is only some deck crews these will loosen over time as the wood deteriorates and then pop out as happened to fair0906. Yes, they will hold a good long while (many years), but the angle brackets take the stress off the screws and place it on the bracket itself and will last longer than the wood under stress.

Once the wood begins to deteriorate and the screws pop out, you can add the brackets to extend the life of the bed. Why not just add them from the get go and be done? That's how I look at it. Besides, with all the moola you save going with a single layer of 2x8s you can afford some really snazzy angle brackets ;-)

I love the idea of the 1/8 interior frame. That way, if I rotate the potato bed, I will have a portable frame.

I will definitely go with the angle brackets. The local hardware store recommended something called "stair reinforcements." Ever heard of them? With the angle brackets, what size should I ask for?

Wouldn't the overlap waste a lot of wood since it comes in 12 foot lengths and I am building 9 4-foot squares?

Thank you!!!

Here is a URL to what a corner bracket looks like. Unfortunately the pic shows a bracket intended for indoor use on cabinets. What you want will look similar, but is more heavy duty and should be weather resistant. What size? On an 8" board get one that is about 6" tall.

--- Wouldn't the overlap waste a lot of wood since it comes in 12 foot lengths and I am building 9 4-foot squares? ---

It will be impossible to make a sturdy frame that retains soil using all 4' pieces. If you are content to have interior dimensions of 4'x3'9" then this is fine. If you want the interior dimensions to be 4'x4' then you need to cut half the boards 4'3". You can get the boards in different lengths most places. The hardware/lumber store near me carries the cedar 2x8s in 8', 10', 12', 16' and longer lengths are custom ordered and are ready within a few days.

If you do the math with the wood cuts, you will find you use less wood if you make those 9 4x4 beds into 4 4'x8' beds and even less if you make 3 4'x12' beds. Less cutting and less wood wasting. However, you may have a very good reason to make them all 4x4, totally up to you.

Here is a link that might be useful: angle bracket pic

A picture is worth a 1000 words - thanks!

I definitely want the beds to be square. Not sure if my math is right, but if you alternate your corners of overlap, wouldn't each side measure 3' 10 1/2"? If this makes sense, then the wood would have to be cut to 4' 1 1/2". Does that sound right. Probably not worth the cost of the wasted wood to just get an extra inch and a half. Again, I'm not sure if I did this right.

It helps if you get some grid paper and draw the interior dimensions 4x4 and then draw the 'wood' on the paper around the interior area to visualize what size the wood has to be.

If you want to overlap each piece then every piece needs to be 49.5" to end up with an interior dimension of 48"x48".

Alternately you can use 2- 48" pieces for the sides and 2- 51" pieces for the top and bottom. This method doesn't overlap with each piece, the 51" top and bottom pieces overlap the 2 side pieces.

Either way uses 198" of wood. Thats 16.5 ft of wood to get 4'x4' interior dimensions.

Now, the thing about 4' beds is that they are too wide for many folks to use most comfortably. I am 5'10" and have 'normal' length arms and I find 40-42" beds a better fit for me reaching into the middle.

My choice is to make longer beds (8-10') and narrower (36-42"). That's just me.

The grid paper and drawing really helped me to visualize - thank you! The wood here only comes in 8 foot and 12 foot lengths. Looks like I'll have to live with a little bit less on the interior to avoid the waste.

I am a little bit worried about the reach factor. But I figure if I could reach from all around, rather than have a long bed, it may be ok. In a perfect world, I would love to have 3'x3' beds, but that would get real expensive.

BTW, I'll be running a drip irrigation system because I won't be able to water daily as the garden is at a remote location.

I think your calculation would be great to add to the SFG website. I don't think I've ever seen it worked out so well :). Thanks again for taking the time.

I do NOT have an answer to your grid question but apparently no one else does either.

Realizing some of us have a less generous gardening budget & some of us are willing to pay many times more than the vegetables are actually worth...I am just sharing what has worked for me.

Just made another frame tonight and realized some things. I can probably make 2 beds for what you are going to pay for the brackets alone.

I do NOT use deck screws, I use sheetrock screws mainly because they cost less and keeps the COG (Cost of Gardening) down. Sure they do rust but I have NOT had a problem. In fact, have even re-used some screws from 5 yrs ago. Deck screws are not supposed to corrode and are required by code when building a deck.

So standing up on my deck, looking at my new bed frame, I thought...hmmm, I wonder what has more force on it? My fat a$$ on this deck (with the grill & furniture) or the sides of the frame? I am by no means a physics expert but I would think if the screws came out of the frame, either the wood was rotten or I did not choose a screw long enough. But I would think the force applied to the side of the bed frame would be much less than the force applied to my deck (screws).

Last year I fabricated something out of 3 - eight foot 2x4's to hang upsidedown tomatoes on (another story). Because I was lazy, instead of putting it in the ground, I decided to screw it using 1 carriage bolt & 1 sheetrock screw. It was 8 ft high by 8ft long screwed to the sides of 2 separate beds (made 5yrs ago). Held up to our winds (surprisingly) ALL summer with buckets and tools hanging from it. In the fall, I decide to leave a bucket with a few rocks in it so I could tell from the window just how windy it was. Well it last ALL winter until spring time when one day I noticed it was blown down. It broke the wood on my oldest bed ripping the screws from one corner bracket (used because I had them). The 2nd oldest bed it broke one sheetrock screw and bent the carriage bolt...hmmm. I disconnected it screwing the broken wood back to the frame & repaired the bent corner bracket.

An engineer once told me, an engineer is someone who can do for $1 what anyone can do for $5.
Gumby_CT

Here is a link that might be useful: Building Beds is Not Rocket Science

Quick, easy and CHEAP wood grids:

Buy a bundle of lath from a lumber yard for about $5-$10. There are about 3-4 dozen 4 foot strips/boards in a bundle. You'll have to double up a couple if you have 8 foot beds.

I just built my first sfg bed, and I just layed down some bamboo stakes for the grid with twist-ties at the intersections to hold them together. Cheap (or free if you know someone with a bamboo grove) and easy.

--Jean

I just built my first sfg as well. I used jute twine, nailed to the outside boards for my grids. Planting was easy, I will keep you posted if I run into trouble later on with this method.

-kim

I use jute twine as well. I works beautifully and I can redo the grid when I rotate crops and shift where my larger spaces (zuchinni etc) go.
My beds are up about 18" which actually comes in very handy, especially for someone with a bad back. Also, you can reinforce the jute grid with metal tent pegs to keep it from shifting.

I posted this in another message, but this shows a nice raised bed constructed with angle brackets and corner posts. You can eliminate the corner posts, if you like, but I think this is a terrific looking raised bed, especially if it's going to be near the house.

I use sisal twine for my grid. At one foot intervals around the outside of my bed, I placed small screws and tie the twine to those screw heads.

Pinecrest

Here is a link that might be useful: Raised Bed with Angle Brackets