Big no on the 2" walls. I suggest 3.5", standard 2x4 width, minimum for walls up to 18" high. Reducing the wall height to 16" will save on form cost.

Over years, concrete does crack. Use two horizontal runs of #3 rebar to keep the concrete tight together at the hairline cracks.

The 3.5 inch thickness is good because it will last forever, yet if for some reason it has to go, you can break it out with a sledge.

Let me know if you need help with the forms.

Cinderblocks work really well for me. Benefits:
* sturdy cement
* easy to install
* can be laid in interlocking races for stability
* can be 'stapled' into place with rebar bent into U-shapes
* can be moved, expanded upon, built up, reduced, used to segregate planting beds...think of legos....
* make good seats/steadying places for your feet/hands when reaching for that last squash
* are ready-made planters (one carrot, garlic, beneficial flower, or herb in each hole) so you lose practically no space at all
* Store solar heat for warming beds all night
* are inexpensively bribed out from local college housing
* make great canvases to keep local kids busy when I babysat...just hand them some chalk.
* won't crack like cement, rot like wood, or lean like laid stone.

I HIGHLY recommend cinder block as a raised bed material! Here's what our Community Garden plot looks like:

We used a single race and didn't 'staple' them because we're not sure we'll be staying in that same area. They work GREAT, I'm very very very happy with cinderblock gardening!

Thanks so much Plot for posting this picture. Last year I checked a book out of the library called "Cinder Block Gardening." I loved the idea and the book is much like SFG in many ways, but I like some of Mel's ideas better. I was wondering if anyone ever combined the two ideas and made it work.

FANTASTIC.
thanks again for posting the pic!!!

Glad I could help!

And one note...becuase Cinderblocks are exactly one foot long, they work wonderfully for squarefoot gardens. We usually lay them down to use as markers, mark the beds with stakes, remove the blocks, and THEN double-dig. Easy peasy.

About forming your beds: check out this link http://www.squarefootgardening.com/html/NG_50_dollar_contest.html#Top and scroll down to "Elizabeth Collado of Marstons Mills, Massachusetts". This is a series of SFGs that have been linked up. Much more actual gardening space available.

In the same page, Cinderblock gardens have been made nice and raised with two races (!). Scroll down to this heading here: "Francisca Rapier, Veradale , Washington". Proves it can be done.

I love the Cinder Block Gardening book. In it, if I recall correctly, it has diagrams on how to lay out a garden as SFG requires, from 4x4 to 4x40 and all the changes inbetween. Post us some links when you're done, I'm sure your version will be much neater than mine. Would love to see it.

The cinder blocks with two holes that I have seen are usually 8x8x16 inches in size (width x height x length), not one foot long. The other common sizes I have seen are 8x4x16, 8x8xx, and 6x8x18. With a 16 inch length, 3 cinder blocks are 4 feet long which still works out well for a SFG. Verify the sizes available in your area.

Some places carry both cement blocks and cinder blocks. The cinder blocks are much lighter in weight; the cement blocks have a smoother surface.

Anna

I was just reading an article in BackHome Magazine where the author made precast concrete panels for a raised bed garden. Basically he made 2x15x48" boards out of concrete, and buried the bottoms 3" down to make a 12 inch raised bed. It looked pretty straightforward, but he mentions they will be quite heavy- around 50 Kg (oh, all right +/- 100 Lbs) each.

Unfortunately, the article (Ready Mix Raised Beds, by Miller Putnam) didn't seem to be available on the website.

The last bit of the article mentioned using vermiculite in the mix to reduce the total weight by around 40%. Isn't that hypertufa? I remember a few years ago there were dozens of threads about that material here on the SFG forum.

Well anyway, you won't be driving cars and trucks over the raised beds, so they shouldn't need to be so thick, they are just holding the soil in. I think precast two inches with some chicken wire reinforcing would be adequate.

Just my two yen.
Eric in Japan

Hi,

I don't think I've posted here before, but I do come over to this forum to read a bit, and I've found lots of good info here. I just wanted to add my vote for the cinderblock beds. I built three last year, and it was a lot of work (worked by myself on uneven ground - i.e solid ledge - with not much more than a trowel), but it was well worth the effort.

I ended up building a fourth bed, which is to the left in the photo (still in progress). It is only one level high. I like it better in some ways because it is less obtrusive visually, (kind of hard to tell the difference from the angle in the picture) but functionally, I like the two-level beds better.

Thanks for letting me butt in!
:)
Dee

{{gwi:12838}}

Gosh, those are pretty beds! Did you cement or staple? And are they a good height to sit on? And what do you use for between them, how far apart are they, what do you mulch them with, do you have a webpage so I can stop pestering you with questions?

While I now do beds with poured concrete, they aren't right for everybody. People in cold climates with the problem of frost heave are probably better to use blocks. Do not go above 2 blocks high!

As was said, 8 x 8 x 16 blocks are basicaly stable. But if you happen to step on one with a lateral force they can roll, causing a fall. As seating, 16 inches is just a tad low. For extra stability and some exta height I recommend the following ....

Construction begins by leveling the block area. At the corners and about every 4 feet along the wall a 5 inch hole is dug. A 3ft section of 3/8 inch all-thread is driven in the center such that it will align with the cavities in the block. The top of the rod is left about 3 inches above the finished height of the block. Concrete is poured in the holes level to the surface the blocks will be laid on.

The block is laid in the usual way. Next, strips of 3/4" treated plywood are cut to the width of the block. You will want the plywood and the cap to overlap at the corners so do the short ends of the bed first with the plywood. Cut the strip to length and measure from the block face to the rod to get the position to drill a hole in the plywood for the rod.If you are going to paint the wood, do so now.

Install the plywood using a washer and nut on the rod.Do not over tighten the nut. After the bed ends are done, do the same on the long sides. On a 4 x 8 bed there may only be one rod in the middle of a plywood strip. This is OK.

After the plywood is attached, cut off the excess rod above the nut. Cut a cap piece from 2 x 10 lumber to size. This time do the long bed side first. The 2 x 10 will be wider than the blocks. cut the length so that the cap over hangs the block by 1 inch. there will also be a small overhang on the inside.
Coat the top of the nut with chalk or crayon. Lay the cap piece in position on the nuts and tap to transfer the mark to the cap. Flip the cap over and drill a 1" wide hole 1/2 inch into the cap. This hole makes space for the nut and allows the cap to rest directly on the plywood.

After doing the long sides, cut the caps for the short sides. Nut holes will probably not be needed for the short sides. Paint if wanted and then attach all cap pieces to the plywood with screws set below the surface of the caps.

FWIW, by using a cap like this you can lose planting space. Some people don't mind - I saw somewhere on the forums a photo posted by someone who had very elegant-looking cinderblock beds, all capped with some kind of red stone. It was really a beautiful-looking flower garden. Mine is more functional (being a vegetable and cutting garden), and I use the holes in the blocks to plant my herbs and a few annuals (I like to plant cascading petunias in the sides that face the neighbors to soften the look for their sake) and so I don't cover the holes. I just leave two holes open every so often so I have a spot to sit.

:)
Dee

if you are using cinders you take up valuable planting space b/c of the width of the blocks. i wood only make the beds 3ft wide then 36+16=52inches wide quite the reach so maybe 2.5ft wide then

This may be a bit off-topic but we built side-by-side compost pits by stacking cement blocks and bricks. We work up one pile until the bin is full and then stop adding stuff to it. New green waste goes into the other bin. Before too long the older pile is ready to be screened and worked into the garden.

{{gwi:298198}}

Here is a link that might be useful: Smith Family Garden

I am a couple of years late replying to this topic but we were just thinking of using cinder blocks as raised beds and we are now planning on doing the exact design as diggerdee.

We love your design!

We currently use 15 large crates that we got free as raised beds. They are in our front yard. What do they look like? Like 15 free large crates filled with plants. They worked beautifully but look pretty bad.

Our cinder block beds will be 3'x37'. We already figured we will need four beds and that is 528 blocks @.99 per block. We are making the beds two blocks high because we love the height.

Our current beds are 2.5' feet high and I just think it is so much easier to garden.

We have plenty of compost to fill every single bed so the only cost is the actual blocks for now. However I will be checking craiglist and freecycle to see how many free blocks we can get that route also.

We are ok with the budget of $528 but why spend that much if we can get it much cheaper.

Diggerdee, how long are your boxes? I hope you are still getting replies to this topic because we really love your beds. We will just put vining or trailing plants in the holes.

frugalque, you've got mail!

I just wanted to add something about the blocks. Sounds like you are getting them at a home depot type place from the price you give.

I ended up having a shipment delivered from a concrete place. I don't remember the price per block, but it was competitive with Home Depot and additionally, I got them all at once. I don't know about your transportation, but I was stopping at HD a few times a week getting 8 to 10 blocks and putting them into my little Honda, so the one-time, big delivery was worth the money, even if I did have to pay up all at once.

Good luck!
:)
Dee

Yep, we will be getting them all from Home Depot but their contractor desk will deliver them all to us for an additional $80 so we will go that route. Thanks for the tip though. I will check around at some local concrete places to see if we can get a better rate.

Since you have had these beds for a few years now, do you have any pros or cons that you would like to share?

We are really excited about this project. I think our neighbors will be happier too. :)

I've made a bit of a retaining wall out of cinder blocks for a garden behind the garage. There was such a steep incline in that spot originally - that I decided to build up two blocks high and level it out. This gave me more gardening space as well.

{{gwi:30706}}

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You can see the overall idea that I used to design them. I didn't place the cinder blocks immediately on top of one another - but made the second layer staggered between two bottom blocks. I also did not use any kind of concrete or mortar mix.

I just had to be very careful to ensure I dug out the area to be fully level - and then plopped the blocks down. I then cut some rebar to about 3-foot lengths and placed in every other block to assist the blocks from falling over. You can see larger pieces of rebar in the last picture above - and those are used to hold up a 3-foot mesh fencing around the area to keep the deer and critters out.

The individual squares were then filled with dirt and the whole area filled in. The squares are just perfect size to place one onion in each - so I get a good 50+ onions in this area.

Here is a link that might be useful: BsnTech Gardening Blog

I am very near buying stuff to build cinder block raised beds and see a lot of comments here on using them, but I have one question that I have not had good luck finding an answer to... If you're in a climate with harsh winters (zone 5, bordering 4), if you fill the holes in the cinder blocks to plant thing in, will the cinder blocks crack/break over winter from the freezing and thawing?

Did you end up using the cinder blocks in the cold climate? How did it go?

Actually I did setup a few raised beds with cinder blocks. I used 8"x8"x16" blocks - standard building size and overall I'm fairly happy with it. Like I said, we have pretty strong winters and even though the holes in the blocks were filled with dirt - none of them cracked! And, for the most part, they even stayed pretty well in place.

I was concerned that the dirt in the inner body of the bed would freeze and push the blocks outward. This has happened a little, but not very much. This past winter was the worst for that, but still not so bad that I'll have to re-lay the block - I just tap them back into place once the soil thawed. I did not use mortar between the blocks - they are dry stacked and loose. I can't say for sure, but I think with the little movement we have experienced, mortar would probably end the moving around - BUT maybe I'm wrong and that hard, static position would fail to the freeze/thaw of the soil. Anyway, I think I like them loose - then I have options. If I want to do something different, I don't have to bust it all apart to change my layout.

One thing we have experienced is that a lot of perennials don't like being in the block holes over winter. Some of them have made it a year or two, but I believe the roots/bulbs/etc... are just too exposed to the freezing temps this way. I mean, you only have about an inch of concrete and then the soil, which is only 5 or 6 inches wide - which really doesn't protect the roots from a freeze very well. Maybe the most interior side of the hole would be somewhat protected, but it's just not the same as being 5 or 6 inches down in the ground with a mulch layer on top. About the only thing that has seemed to handle it very well are some Asiatic lilies. We've tried tulips, crocuses, a few kinds of non-bulb flowers (can't remember their names right now), a few kinds of ground covers, etc... but none have held up for long.

Part of the problem is that the soil freezing and thawing causes the soil to heave up and then in spring it thaws and settles. I don't think the plants like this much. Strawberry plants have done fair, but generally after a winter, they're almost lifted out of the soil. Our soil tends to settle as well - I'm sure it's our mix, as there are a lot of organics that I think still continue to degrade, so the soil level drops - so over the period of a year or two the soil that was 1/4" below the top of the block might be 6 inches lower. So, that strawberry plant that was getting nice sun, ends up in the shade down in a hole.

So, trying to use the outter holes for anything other than annuals has been difficult to impossible.

Our soil mix BTW, is 1/3 compost, 1/3 peat, and 1/3 vermiculite. This makes a nice light soil that retains moisture pretty well and has a nice nutrient mix. Very easy to pull the occasional weed from. You can drive your hand right down into it.

Lastly, when you prepare the ground for using cinder blocks, you really need to spend time initially making sure that you have the surface where the blocks will set very square (I mean 90 degree angles - not a square shape), level, and flat. I tried eye-balling it at first, but it became apparent very quickly that things were not lining up properly - leaving gaps vertically and horizontally between the blocks - which will make them less stable and a potential for losing soil and water. Then I had to move all the blocks, star over, and then re-set them up. I didn't make that mistake with the remaining beds!

I think the bed shape I like best so far is 2-1/2 blocks by 4 blocks (you could go longer, but I like the 2-1/2 wide dimension). This is wide enough to plant a batch of stuff and not have it too crowded. We did a couple of beds 1-1/2 blocks wide, but the center growing area is only 8" wide - I fee like it's just too small - but that was all the space we had to use, so no choice. This thinner design has done ok with lettuces and some smaller items, but they can get crowded so easily.

The main point is that is has been a success in my view. No busted blocks. It's easier to maintain (I don't have to be down on my knees at ground level working). I think it helps keep weed seeds from getting into the beds as easily since they are up higher. Etc... About the only thing we have to do is to add more soil each year as our soil mix degrades and settles more.

Hope this has been useful information for you.

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