I used screws for my raised beds instead of nails.

I used 4x4's for vertical supports and 2x12's for the runners.

I used redwood. It really weathers well and resists rotting (not that it's an issue here in Arizona.

If you put holes in the bottom to allow for drainage, put some landscape fabric down to prevent your soil from falling out.

I am not raised bed expert, but from what I read, 8'x12' is not recommended size;
it is not the lenght (I would call 12' lenght), but 8' wide is too wide. Maximum recommended width is 4', so you can reach halfway from each side. That way you can work to the middle of the bed without having to step in it. So in your case it would be 4'x12'.

I think you would like to do "square-foot gardening" - so you will have 4 squares width-wise & 12 squares lenght-wise. You can plant more than 1 vegetable into 1 square. It depends on their size.
Redwood & cedar would be best woods to use since they will last longer (also most expensive). Do not use pressure treated wood for veggie garden. You can buy boards in lenght you need to avoid cutting them yourself. I would also use screws, and buy deck screws (they will not rust). You can use 12" wide boards, or stack 6" or 8". You can build-up any hight you need. The sides would have to be also supported at regular intervals, otherwise sides will bulge out (I would put vertical support every 4').
You can stack them like steps, starting with a lowest bed lets say 8" deep (for veggies with shallow roots), next bed deeper (12") and so on.

Why are you planning on giving them "bottom"? Are they going to be on concrete or something similar? You definitely need drainage.
Rina

Good drainage and depth are definitely considerations, and I think the idea of being able to reach halfway across is another great idea. You want to make it as easy on yourself as possible.

If you can possibly lay the raised beds directly on the ground, that would be the best option. No bottom would be required, which would be helpful for both drainage and root expansion.

If direct contact with the ground IS possible, I would begin by stripping the sod to the dimensions of your raised bed frame, lay the frame within, and voila! You have easy to maintain beds.

If direct contact with the ground is not possible, then I'm not sure what the best bottom material would be. You don't want to use any type of cloth or screen that will be too fine... you'll end up with clogged drainage, depending on the medium used.

If it is possible to lay the beds directly on the ground & there is sod, I would not bother with stripping the sod.
I would just put thicker layer of damp newspaper (at lest 6-8 sheets thick) or even better damp corrugated cardboard (from boxes) directly over the sod (to fit inside of the planter/raised bed).
The paper will slowly decompose (it will take definitely whole season) and keep the grass from growing thru. Next year there will be no more sod, just fertile soil in there. I have done this so know it works. I also used shreded paper. Had some manure, so put it over the paper and some shreded leaves over that. Veggies liked it a lot.
I grew peas, tomatoes, celery, swiss chard, basil (4 different kinds), chives & more in this bed. I had 6 tomato plants there & more tomatoes than I could consume.

I did not build frames from wood, but used concrete blocks I had laying around.
Rina

NOTES: This is long but as stated, I've never built raised beds before, so have tons of questions. Sorry if some of them are dumb. Somebody also suggested the use of either 12" boards or 6"-8" boards. Is this for the 4' x 12' raised beds?

Also if I'm making the 'stair case' raised beds, can I still do the 4' x 12' set up?

Also thank you for the advice and suggestions given.

Although I want to have the beds divided into 4-6 squares for root veggies, I don't want to do SFG. Sorry for not clarifying this earlier.

It was said the sides had to be supported, or they'd bulge out. How would you support the sides?

When you say the beds should be on the ground, are you talking about they need to be on the dirt? I have a walkway I garden on that is made of concrete so should I not put the raised beds there?

A very stupid question about drainage but if there is no bottom and it's just lying on dirt, how does it drain?

Would the water pool at the bottom, or if you put newspaper on the bottom, would this act as a cushion and absorb tbe excess moisture?

One of the problems with my storage containers is there tend to be extremes in temperature fluctuations, and they heat up very quickly.

Do these problems exist with raised beds?

I had a question about the size of the boards mentioned. You said you could use 12" wide boards or 6"-8" wide boards.

Is this in regards to if I were to make a 'stacked' (staircase) raised beds?

I also had a question in regards to the size of the boards mentioned, and building up the height (to make the beds deeper) of the bed.

It was told to stack the pieces of lumber. So I wanted a depth that is 36" how many boards would I need to stack on top of each other?

Would this stacking of the boards also apply if making the 'staircase' raised beds?

The last question I have is in regards to the newspaper on the bottom. You said use a stack 6-8 pieces thick of newspaper. I'm assuming this would just be 6-8 pieces from one newspaper or 6-8 newspapers? Sorry if the question sounds dumb, I've just never done this before.

Also I make my own soil mixture (it uses perlite, peat moss, dolomitic lime, and some pelleted fertilizer designed for container gardening). So would I have to put
compost on the bottom of the newspaper, or would this be overfertilizing?

I ask because I totally screwed up fertilizing with my soil mix last year by usin a fertilizer that wasn't suitable for containers (I didn't realize this till after I used it).

Had to throw out my soil mix, make a new batch, and didn't have time or money to add a fertilizer that was designed for container gardening. Tried to compensate by using a liquid fertlizer on the surface and this just made things even worse

*boards of any width could be used: 4",6",8",10",12"...depends how deep bed you want. For 24"deep you need to stack 2 boards 12" wide (or 3x8", or 4x6") - regadless of length of bed.

*stair-like design could be any lenght too-depends how much room you have

*side supports stakes should be similar to corner stakes - I would probably use 4"x4" for corners, and 2"x4" for side supports.

*if you plan on having them on concrete walkway, they should have bottom with drainage holes
if you put beds on ground (soil-dirt-grass) you don't need bottom, they will drain directly into dirt

*the newspaper/cardboard is used to get rid of grass without digging it up & it will decompose so no problem. But if you garden on concrete, you don't need to worry about getting rid of grass - so you can forget about the newspaper/cardboard...

*you probably used plastic containers (?) - they would heat up much faster than raised bed made of wood

*there is many plans available on internet, just google "raised bed plans" or "how to build raised bed" or something similar...you will get many great ideas

Hi Kawaii,
It is important to understand the relationship between the earth and a true raised bed, as far as drainage goes. Please understand that it is in no way similar to the drainage charateristics of a container. The earth will act as a huge wick, providing excellent drainage characteristics, as well as providing a place for the deeper roots to colonize. This is why many people with "slow" soil opt for a raised bed. In my opinion, if you have the room, it should be set in ground. If you put it directly on concrete, you are going to need to be very smart about how you provide drainage to the bed.

Also, you are talking about a 36" deep raised bed. This is VERY deep, and totally unnecessary, specifically if you are in contact with the earth. Not to mention, that just one 4'x12' bed at that depth is more than 5 cu yds of fill.....I hope you know someone with a very big truck.

This amount of soil will also put HUGE forces on the walls of a 36" deep bed, you will need to construct a VERY structurally sound bed to resist these forces. Were talking multiple TONS of soil. A few finishing nails and 2"x4" supports is not going to do the trick. If it were me building a bed of this size, I would set (6) 4"x4" support posts (one at each corner, and one at each 6' midspan) 18" deep in concrete and use 4" screws every 3" to anchor the runners (3 screws per 12" board at every support post).

Please don't take this the wrong way, but it sounds like to may not be totally prepared for an undertaking of this magnitude. I suggest that you start of with 12" deep beds (use 12" runners...easy peasy), set directly on the ground. At this depth you can simply sink your supports a few (~4) inches into the soil to prevent lateral movement, no concrete required. Make a 5-1-1 mix modified with an extra fraction of peat (5-1-2) to fill your beds. Only the deepest roots will utilize your native soil, while the feeders and more shallow rooted plants will enjoy a life of luxury in a fast draining, well aerated mix.

That just my 2 cents.

PJ

This is a long post, sorry.

Hi; thanks for your advice and taking time to post.

The wood used is pine, and it's 2' x 12' and 1-1/2". Is this strong enough. Didn't realize 12" was enough for depth.

I'm not used to roots growing thru the normal dirt, because my containers have bottoms, whereas raised beds don't.

Am not DYI person, so sorry about the next questions. What are support posts, and what is mid span?

In container gardening, my soil mix dries out very fast; there are huge fluctuations in temperatures too. Are these problems with raised beds or no?

Somebody suggested using newspaper on the bottom of the beds. If the ground acts as drainage, is this necessary?

In container gardening, you shouldn't use real dirt (from ground) in containers because it's too heavy and compacts.

Is soil compaction a problem with raised beds?

Somebody also said they added a layer of compost at the bottom of their raised bed. My soil mix (make myself) already has fertilizer in it (dry and pelleted, Oscomote).

If compost was in bottom of beds, along with the fertilizer in the mix, would this be over kill with fertilizer?

I ask this cause I screwed up my soil mix last year by using the wrong type of fertilizer (used a variety I didn't realize wasn't suitable for container gardening.

Had to remake batch, didn't have time or money to add correct fertilizer. Tried to compensate by using liquid fertilizer....caused stressed out plants, decimated harvests, and way too many aphids because of excess nitrogen in soil.

Kawaii, the soil you use in raised beds is different from soil you use in containers.

You can use more "minerals" (sand, silt, clay) in raised beds.

The earth underneath wicks the moisture away, so your soil in raised beds should be more water-retentive than in containers.

I asked this question the soil forum about everyone's favorite ratio of mixes in raised beds. It was an interesting discussion.

Here is a link that might be useful: Link to the discussion about soil in raised beds

I agree with the replies above. One note though. If you set directly on the ground, you can use regular garden soil as the ground will work as a wick. If you are setting on concrete with drainage on the bottom, it is no longer a raised bed, but a giant container. You will not have the wick effect of the ground and will need to use a soil mix more suited to containers to allow drainage. I also agree with the points above that you are best off directly on soil if possible. Putting such a large container on concrete makes the entire design much more complex. You'd be better off with smaller boxes or containers on concrete.

"The wood used is pine, and it's 2' x 12' and 1-1/2". Is this strong enough. Didn't realize 12" was enough for depth."

4'x12'x2' is still a pretty big bed, and your intention is to build more than one, correct? You do understand how much fill that is right? And how much it will cost to acheive?

Anywho, the strength is not the issue with pine. Pine is a soft wood, with open grain and high cellulose content. This makes is highly susceptible to termite damage, rot, etc. It's plenty strong to build with, just not at all what you want for this application.

Something like redwood or cedar will be your best bet, if you want untreated wood. You could also use pressure treated wood. If your worried about it leaching toxins, just line the walls. Another option would be to use concrete blocks.

"Am not DYI person, so sorry about the next questions. What are support posts, and what is mid span?"

Support posts are support posts...idk...corner posts, whatever. A mid span is the middle of the span - mid span. If you can't answer these questions, you may want to hire a carpenter. No offense intended.

As for soil, bed liners, compost, fertilizers....if you ask 100 people, you will probably recieve 100 answers. If it were me, I would clear the sod and not bother with newspaper and such on the bottom. Drastic changes in soil composition or any type of barrier layer tends to make the water perch at that point, you want it to be wicked away cleanly. As I said in the previous post, I would personally use a mix very similar to the 5-1-1, only with an extra fraction of peat (5-1-2). I would mix a good amount into to top few inches of native soil first, then dump in the rest on top. This will help create a transition, as opposed to a hard edge.

That makes 4 cents.

LOL.

Good Luck!

PJ

Agree on the 5-1-1 or 5-1-2. Bark is relatively cheap, and you can use it on both concrete or soil. For on the ground it would still cost more then a regular garden soil mix, but would be a superior performer.

Has anyone seen a definitive answer on using pressure treated wood without liners? I realize modern pressure treat is much safer then the old arsenic based stuff, but I've read conflicting arguments on the issue. I would like to use it as cedar is extremely expensive where I live. All my raised beds I have now are built with concrete blocks left behind by the previous property owner, but I've run out.

The reality is, arsenic is everywhere. It's in the water, it's in the soil, and it�s in your food. Every one of us consumes it on a daily bases. It's only acutely toxic in high concentrations, much higher than what could be absorbed by a root vegetable; unless of course your wife is trying to kill you...wink. Even with the old PT wood, you would have to consume all, or at least most, of your entire diet from that bed....for many years....to see any chronic ill affects.

Today's PT is all copper based, which as we all know, has very low toxicity to mammals. In fact, I would think that the plant would die long before it actually absorbed the amount of copper required to be dangerous to humans.

Unless you�re concerned with copper runoff to groundwater or growing in a certified organic environment or if you really do eat most/all of your diet from the bed, I wouldn't be concerned in any way about using unlined PT.

That's just me though.

PJ

Well come to think of it, one of my large (5x5) compost bins I built was made from copper treated PT...

Thanks for the answers w/questions.

NOTE: I really screwed up my soil mix last year by using the wrong fertilizer and too much fertilizer. This really created problems, and i really don't want to botch my soil mix again.

Not to be rude, but some weren't answered; sorry I'm not trying to be ungrateful, my apologies if it comes off this way.

With a 4' x 12' bed, does it need the support of the posts and concrete (the depth would be 12"). What is wicking? I don't know.

Went to lumber yard, they suggested pine. They have cedar, it's pressure treated; is it still safe to use?

W/compost, don't have room to make my own; even if I did, wouldn't be ready in time. Read on threads that commercial compost is essentially sewage. Is it safe to use?

Two questions about compost. I realize there will be 50 different suggestions on what soil mix to use in a bed.

My only concerns w/compost are...

Will it make the soil mix too heavy/compact and/or will it cause the veggies/plants to become waterlogged?

My soil mix uses lime, pine bark mulch, perlite (or vermiculite), spaghnum peat moss, and a dry 19-6-12 fertilizer (Osmocote).

Since mix already uses fertilizer (mixed in when I make soil) then will adding the compost be over kill?

W/my soil mix if I were to use compost, then would I reduce one of the ingredients in the soil mix, and replace it with the equivalent amount of compost (if I reduce my peat to 3 gallons, would I replace it with 2 gallons of compost).

Or would I keep all the measurements in the original soil mix exactly the same, and just add compost to the existing mix? If so, how much?

kawaii, you asked about compost in raised beds: "Will it make the soil mix too heavy/compact and/or will it cause the veggies/plants to become waterlogged?"

The short answer is NO.

MOST people will say that your container recipe (bark/perlite/peat) does NOT retain enough moisture for raised beds.

You asked: "W/my soil mix if I were to use compost, then would I reduce one of the ingredients in the soil mix, and replace it with the equivalent amount of compost (if I reduce my peat to 3 gallons, would I replace it with 2 gallons of compost)."

Here is my answer: You will get a different answer from every single person.

This is why: Container culture is pretty much the same across the board, but raised bed gardening has a LOT more individual variables. So you're not going to get a consensus statement when it comes to soil in raised beds. :-)

Al (tapla), who devised the 5:1:1 recipe for containers, uses a totally different recipe for raised beds. I hope he doesn't mind, but I'm going to copy his answer from another website:

"I would suggest a raised bed soil would be about 70-80% mineral components as the structural base - topsoil, sand, fine Turface ... and 20-30% other organic ingredients to make up the rest. It won't matter much what the organic ingredients ARE, because at that low % they won't affect the structure much as it relates to drainage. I think that finished compost or pine bark fines are an excellent addition because neither will significantly immobilize nitrogen (even if it does, that's fixable). Reed/sedge peat is another good choice."

But there are RB gardeners who successfully garden in almost 100% compost.

You asked: "Read on threads that commercial compost is essentially sewage. Is it safe to use?"

My answer: Purchased compost does not NECESSARILY contain sludge or sewage material. You might have better luck finding good compost from a local source (like your county) rather than in bags at the store.

I'd love to link you to al's discussion of raised bed soil, but it was caught in the spam filter. Apparently, I can't mention DG dot com by name.

Al's comments on raised beds were based on it being in contact in the ground and having the ground wick away water. For your question on wicking, the ground will tend to pull away excess water, which is something you won't get if you put a bottom on and sit on concrete which in reality makes it a large pot. When built directly on soil, you really don't need the full drainage of 5-1-1. 5-1-1 will work, but you can always add native soil and compost due to wicking. If you are in contact with the ground, I suggest you use a more organic approach to fertilization since excess will be pulled into the ground. This would include compost, fish emulsion etc. I would only use synthetics to deal with deficiencies, but not as your main nutrition.

Can you give me a link to the excerpt that you put regarding the recommendation of the soil mix you described for raised beds?

This is the excerpt I'm referring to....

"I would suggest a raised bed soil would be about 70-80% mineral components as the structural base - topsoil, sand, fine Turface ... and 20-30% other organic ingredients to make up the rest. It won't matter much what the organic ingredients ARE, because at that low % they won't affect the structure much as it relates to drainage. I think that finished compost or pine bark fines are an excellent addition because neither will significantly immobilize nitrogen (even if it does, that's fixable). Reed/sedge peat is another good choice."

The only other mix I've found of Al's is his gritty mix. Here is the 'recipe' for it from garden web (am going to copy and paste the text, and a link).

I'm trying to make a guide for the gritty mix for my website and everyone here to use, am I missing any useful information ? I added some photos however the are not working.

Al’s gritty mix is a coarse potting mix that provides great drainage and great aeration. It is long thought through mix by Al from Gardenweb.com website. Many members of GardenWeb use it and it cannot be praised enough. By using 2 inorganic material and fine bark, the mix lasts very long before breaking down. The Gritty mix is recommended for any perennials plants or anything that will last more than one season. The ingredients for the gritty mix are 1 part Turface, 1 part Granite Grit, and 1 part Fine bark.

The ingredients are:

Turface (heated clay). It is used to hold water and nutrients. Look for size "Turface MVP". John Deere "Turface AllSport" is the same.

Granite grit. It holds no water or nutrient at all. It is used to provide better drainage and reduce water retention. For brand "Gran-I-Grit" use grower size. For other brands, the ideal size is 1/8".

Fine bark. It is used to hold water and nutrients. Use uncomposed "Fir" or "Pine" bark. Ideal size is 1/16" to 1/4".

Gypsum for CaSO4 source. Add 1 tbsp to every gallon. Epsom salt for MgSO4. Use 1/8 -1/4 tsp Epsom salts per gallon of fertilizer solution.

Adjusting the mix

This mix can be adjustable to your needs. For better water retention add more turface, less granite grit, and same amount of fine bark. EG. 4 part turface, 2 part granite grit, 2 part fine bark. For better drainage, aeration, and less water retention, you can use 4 part granite grit, 2 part turface, 2 part fine bark. I don’t recommend using too much granite grit, however, as you will have to water very often. The original 1:1:1 ratio already has much more aeration and drainage than any other potting mix out there.

Preparing the materials

It is recommended that all three ingredients be screened with a window insect screen (usually 1/16"). Fine bark should be screened with a 1/4 hardware cloth to get rid of the larger particles on top before screening the rest with the insect screen. It is also recommended that fine bark be left out to dry for easier shifting.

The mix that you copied and pasted for the soil Al created for raised beds sounds very different than the gritty mix.

One last question; the excerpt says use 20%-30% organic matter. I'm going to assume the organic matter is in reference to fertilization of the mix in the raised beds?

It was said don't rely on synthetics for main form of fertilization when making an organic mix for raised beds.

However could I use the osmocote in combination with compost, etc. Or would be it be better to just use the compost?

If using only compost for fertilizing, then should it be various kinds of compost? That is, one from a cow, another from a chicken, etc.

Great points Capo and ssmd,
I think that, K-neko, you are making a mistake. One that I think everybody does, for the most part, I know that I did. You're looking for a one size fits all answer to all of your questions wrapped up in a nice little package, you will not find it. This conversation is a great example of how, as ssmd said, and specifically with in ground or raised bed gardening, your going to get ALOT of opinions. Around here, most everyone is on the same page for containers, not so much with in ground or raised beds.

ssmd said:

"MOST people will say that your container recipe (bark/perlite/peat) does NOT retain enough moisture for raised beds."

I am currently growing some eggplants (and some filler annuals and herbs) in a raised bed. I use a 5-1-2 w/ 2 parts peat. I would disagree with the statement above, in that, it does retain plenty of moisture, IF....IF you are WILLING to PROVIDE the necessary moisture, which for me is daily, maybe twice a day. Now, I also live in Miami, it's in the mid 80's already...so this WILL be a totally different experience than someone using this setup up north. I like watering/fertigating every day. My personal goal is to provide my plants with a habitat that ALLOWS me to wine and dine them EVERY DAY. But that's just me.

If you want to create an environment for your plants where you can watering them once a week, and feed them organincs a few time a month....go with a mineral based mix as suggested above. It will yield amazing results, no doubt.

If you want to tend your plants daily, go with something more along the lines of what I do.

It's all about you, my friend....and your plants of course. Do what makes you happy, in a way that you can provide the absolute best possible environment for your plants. Understand that the best environment that you can provide might not be the same as someone else on this forum. There are all kinds of factors....how much time you have, how much experience you have, what kind of plants are you growing, how many zeros are on your paycheck, how big your yard is, what resourses you have available to you....the list goes on and on. You can reach the same ends in many different ways. Slow down, take a deep breath, we're not sending our plants to the moon after all. Figure out what it is exactly that you want to accomplish, then go for it!! At some point you've got to just jump out of the birds nest.

Most importantly, HAVE FUN!

PJ

Rather than a 4' x 12', three 4' x 4' beds may be more convenient.

Kawaii, as I stated earlier, gardenweb CENSORS some of the links. It would not let me directly link to that discussion of Al's, because it was on another website (a competitor).

:-(

I think PJ has some wise words there. It seems you're missing some of the "big picture" issues we're discussing and focusing on some of the details.

Hi Kawaii - let's see if I can get a few links in here. The first is a Sunset magazine article on how to build simple raised beds (I always find pictures help): http://www.sunset.com/garden/perfect-raised-bed-00400000039550/ A local nurseryman made mine for me (linked below). They're 8 foot by 4 foot and you can see he used plumbing supplies to thread a pipe across the middle of the 8 foot bed so it wouldn't bow out. He braced the corners on the outside, Sunset does it on the inside. I put the hoops on myself (instructions with pics on the blog post below).
This post has a few additional shots of the beds: http://ceodraiocht.wordpress.com/2012/03/25/hope-springs-eternal/
There will be arguments about what's "poison" and what's ok - I used an acrylic water seal to make my beds last longer as we have solidly wet winters for months.
Pine is less expensive, but will you be disappointed if you're beds fall apart in two years? Redwood or cedar will REALLY last, but generally treated is something I avoid for food beds. You should be able to find untreated redwood or cedar easily. Some folks use treated and line it with heavy plastic between the side and dirt.
For veggie crops, I like to add bagged composted steer manure (cheap and I have a lot of room for planting mix) to my beds at least a month before planting. Veggies grow and produce your food in one season so most are heavy feeders (not so much for herbs, tomatillos or tomato, but I like pumpkins and squash).

Here is a link that might be useful: My Blog - Raised Beds Post

kawaiineko_gardener, would you please explain why you are not doing Square Foot Gardening? Don't let the idea that you have to restrict yourself to 6" of soil turn you away.

Homemade compost lets you determine its contents. You originally mentioned an 8ftx12ft garden. A 4ftx12ft would leave you with room to compost this year. You could always add another raised bed next year.