Depth of a SFG?

halfdozendoxiesApril 1, 2008

Okay folks I have another question. I know Mel repeatedly says that 6 inch deep beds are more than sufficient for virtually any gardening needs...but I'm not convinced. I was hoping that people would be willing to share their experiences with me. I don't want to go deeper than necessary due to the cost of filling each bed, but I don't want to go too shallow and have my attempts fail. What depth have you used and what kind of vegetables did you plant? Thanks to all!

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Is your beds built on top of something hard - like cement? Mine are 6 inches above the ground but the bottom, made of newspaper, has long since disappeared. Good dirt is underneath so it's never been a problem. The roots that may need to go deeper than 6 inches (I doubt if there are any) can do so.

    Bookmark   April 1, 2008 at 8:25PM
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I am building my beds on grass. The plan is to place a high quality weed mat under the base of the bed to prevent any weeds from working their way up and into my beds. Then of course I will place the "soil" on top of the weed mat and away I go.

    Bookmark   April 1, 2008 at 9:20PM
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sinfonian(U8b A2 S5 SeaWA)

By weed mat, do you mean landscape fabric? That's what I used. As for the depth of the beds. I'm a new SFG but I built mine 16.5 inches high, knowing it would cost more to fill. My brother convinced me to go that high because after a decade of his beds being 6 inches high, he wished they were much higher. That was enough for me.

Here is a link that might be useful: Sinfonian's gardening adventure

    Bookmark   April 2, 2008 at 12:32AM
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It is similar to landscape fabric but is much tougher than the products that they sell at the big chain stores. It is actually made from some type of woven plastic and is very, very strong. The weave allows the water to easily drain away but it also gives the stuff tremendous strength. I tried pulling it to see if I could get it to tear and no matter how hard I tried I couldn't damage it. Anyway, I have already bought enough lumber to build my first bed and it will be 8 ft long, 4 ft wide, and 12 inches deep. I thought I could plant the heavier rooted vegetables in here and then get away with more shallow beds for other make this endeavor as economical as possible. May I ask what was wrong with the 6 inch beds that your brother had? Did things not grow properly or did he not like the look of them? You input is appreciated!

    Bookmark   April 2, 2008 at 3:18PM
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snibb(Salt Lake City)

6" is all you need. Unless you want to grow potatoes and longer carrots. I was part of the original experiment with this. We put a 3X3 patio box on the cement(these boxes have a plywood bottom on them). We then put a 3X3 in the garden. We then grew 2 kinds of carrots in each one of them, the "thumbelina" type and a longer type-I thing they were danvers. We pulled them up at the end of the growing season. The one in the patio box-well, as Mel likes to joke, it tasted like and "L". Thats what it looked like. But, they did grow. We also grew lettuce, beans, and beets. There was no difference between each box-one with the 6" of soil, the other with about 12" of soil. Mel did come up with a way to grow these longer root crops which enntails making a "high-rise". It is a 1X1' box that sits right over an existing square. You can read up on them(and see them)on the
You can go deeper, but, it only really adds to your cost. Check it out and let us know what you think....

    Bookmark   April 2, 2008 at 8:09PM
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Thanks for the posts! Snibb...I was hoping to ask you some questions but when I tried to email you the email was returned as undeliverable. If you wouldn't mind, could you please send me an email so that I can respond with my questions? I would really appreciate it.

    Bookmark   April 2, 2008 at 9:36PM
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Long story but... last year, I had a couple of beds dug out for me. The guy (read day laborer) and I went to home depot. Although there was a language barrier, I did understand that he wanted me to buy compost and peat moss. So I did. He mixed the compost and peat moss into the new beds. These were not raised beds but just a mix of my crappy, cemented soil mixed with compost and peat moss.

At this point, before hiring him (read picking him up on the side of the road), I should add that I did manage to dig out another bed on my own. It took me a full week of digging up grass and turning the soil. After the first inch of dirt, I tried using everything short of a jackhammer to break up the compacted sand below. It was a nightmare!!!

Getting back to my guy (again read day laborer). In one day, he dug up an area three times the size the bed that I worked on for a week. He mixed in the compost and peat moss. And together, we planted veggies.

That was my first experience at growing veggies and everything thrived. Knowing the soil on my property, I can only attribute the veggie growth to the compost. So this year, my motto is compost, compost, compost.

For the record, I lucked out when I picked this guy up. Because of his help and honesty, I had a thriving garden. I was quite grateful. And every week last summer, I made it a point to drop off fresh veggies for him and his family.

So, while I not have the best answer to the depths of the beds, I do know that a few inches of compacted, cement-like soil mixed with compost and peat moss gave me quite a fruitful garden.

This year, I am expanding the garden. I dug up the grass. I am going to build four 4 x 8 beds. I am using 8" boards instead of 6" boards so that I don't have to be too concerned with leveling the ground below. Gives me enough room for error and as long as the compost is there, I think it should work!!

    Bookmark   April 3, 2008 at 2:42AM
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snibb(Salt Lake City)

halfdozen...I dont know why it shows my email address what it is....this is the correct email address:

    Bookmark   April 3, 2008 at 9:27AM
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tigerpurring(Zone 9 Tx)

I had a similar question; I wasn't worried too much about productivity as water retention (or the lack thereof).

I'm in Houston and this year feels already like it's going to be dry. Because I want my twins to be able to access them, my beds will probably be only about two feet wide (the twins are only three years old).

My gut feel (not always right!) is that in warmer places, a deeper root zone would allow more constant water content and also prevent the roots from getting too hot. Further, our narrow bed would allow a greater surface area to volume ratio than the usual 4'x4' bed (counting the sides of the bed as surface area), and allow the soil the dry out quicker than it should.

Or am I just thinking too hard?

    Bookmark   May 3, 2008 at 1:00AM
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Ray_Scheel(z8b/SS31 E. TX)

Tigherpurring: I'm just a couple counties north of you, and mitigating the heat is part of why I've gone with shallow but bottomless beds. I start out with the paper layer to smother what is underneath and slightly overfill with compost, and as the paper eventually decomposes the plants have unrestricted access to the deeper ground moisture.

Also, in true desert areas, sunken beds are recommended to maximize moisture retention.

    Bookmark   May 3, 2008 at 8:43AM
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tigerpurring(Zone 9 Tx)

Ray, thanks for responding. I thought of accessing the soil beneath, but . . . my patio is full of sand and carefully-arranged limestone pavers from the previous owner to my townhouse. Wouldn't most vegetable roots avoid extending into the sand (not to mention the rocks, ha!)?

If the sand isn't a problem I can move the limestone (oof!), but I'd sure hate to try to dig up all that sand. I know my twins will make a mess of that in no time!

Thanks for helping, T.

    Bookmark   May 4, 2008 at 12:23AM
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Wait, I'm confused. I was thinking that the deeper beds would mitigage the heat better and prevent the soil from drying out as quickly.

But then again, I guess Mel wouldn't be lecturing around the world to people struggling in drought zones if 6" didn't work.

I just personally prefer the height of 12" boxes, but I might simply fill them to 8" and go the full height for deeper crops.

Thanks for you pros that comment on these.

Snibb... are you part of the SFG organization? You seem pretty knowledgeable about Mel's research.

    Bookmark   May 4, 2008 at 11:08AM
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snibb(Salt Lake City)

kristimama...I was an apprentice with Mel-I learned at his feet. I spent an entire summer with him doing all kinds of things and asking all kinds of stupid questions. I am a member of the SFGF, and Mel and I speak a couple of times a week. He puts me in charge of one of the gardening projects we have here in Utah. It only lasts about 10 weeks or so, but, it is really fun to be a part of it. He has me testing all kinds of things here in Utah, and I usually meet with him over lunch up in Eden, Utah to talk about all the things we try to do. The last research thing we did was a compost test. It was a lot of fun, very scientific and it was very interesting. Out of that experiment, we now recommend using only one kind of compost(commercially purchased that is)unless you are making you own. He has me try out all kinds of things, which is why I have some of the weird ideas that I do. He is a very, very intersting guy. It suprised me that he has never been on this or any other SFG blog. SFG blogs were created because of what he invented, and here he is, not the least bit interested! Well, he is awfully busy doing all the humanitarian things that he is involved with. On occasion, there are some pretty out of the ordinary things on this website that I read. I will mention to him some of these ideas for us to maybe implement. The water tank think was the latest-have you seen that? That thing is great! The only problem is the cost though....

    Bookmark   May 5, 2008 at 10:08AM
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Ray_Scheel(z8b/SS31 E. TX)


I'm on a (mostly) sand hill, I filled my kids sandbox by pulling back the top 6" of topsoil/loam and digging out the sugar sand under that for the sandbox. I'd have to go 10' down in some places to get past the sand, so I don't even try to dig it all out.

There are two types of plant roots. The feeder roots going after nutrients stay near the surface, (where your compost is), but they also send out roots aimed more at water gathering that have no qualms going into sand when looking for water.

If I'm understanding your description correctly, I'd sketch where the stones are, number them as you pull them up, and stack them somewhere (so you can eventually put them back if need be), then fill the resulting hole with compost (and possibly some vermiculite) and call it a garden bed.

    Bookmark   May 5, 2008 at 3:40PM
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Snibb... that's so cool to be so close to "Da Man."

You said something about the 1 kind of compost. Can you elaborate on that a bit? Has Mel put that up on his website?

I'm just getting ready to build my boxes next month and I'd LOVE not to have to track down 5 different composts.

Did one particular kind work better than the others?


    Bookmark   May 5, 2008 at 10:10PM
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snibb(Salt Lake City)

kristimama...we had 12 or 13 different composts that we tested. It all started from the fact that we are trying to find people who would be interested in packaging Mels mix for sale. So, we get all these different composts that people send to us that they say is the best. We have actually tested many more than that over the years. But this past year, we had all these samples. We also had cow and horse manure that people swear by. We bought packets of seeds with the same lot numbers and planted in each cell with all the different kinds of compost. We also used the same amount of water in each one every day. We used a heated mat under them all. When the plants were up and growing, we bottom fed them the same amounts of water. They all got the same amount of light and it was a constant temperature. The control we used was the normal Mels mix. Our results showed that 1)nothing beat Mels mix. 2)not all compost is created equal-there are some products out there that are simply not very good-cow/horse/and turkey manure being some of the worst. 3)Once the plants are up and growing, there are still differences we certainly saw. Just because something came up quicker didn't necessarily mean it would grow better or stronger. 4)The best producer(next to Mels mix)was without question a product called "Gardeners and Bloome" compost. It is a Kelloggs product and they may end up making Mels mix next year. It is not on the website but I can tell you it is what we sell when people buy the "batches" of Mels mix. You get a bag of vermiculite, a bag of mushroom compost, peat moss, and this Gardeners and Bloome compost. I think we overprice it though. Dont make the mistake of getting the soil amender-totally different. The Kelloggs product has 8 or 9 different things in it and when you open it, you can tell it is really good. We have done the same kinds of things with vermiculite vs. perlite vs. utelite. We have tested lettuce as well as flowers. Its all very interesting....

    Bookmark   May 6, 2008 at 2:07AM
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Snibb... this is really interesting. I like the way you provide the background information... it's one of the things I liked about how Mel wrote his latest Introduction... about how and why he tested things. In a way, he has and is challenginge long-held beliefs about growing so I really like reading all this.

Hmmm... why the mushroom compost? Can it work fine without the mushroom compost?

Also, care to talk about the tests of vermiculite vs. perlite?

And finally, when you say "Mel's Mix" above being still the #1, are you talking about the "Mel's Mix" that was with 5 parts of different composts?

I'm in Ca, so we have Gardner's & Bloom products here in the Bay area, but if people don't have access to that brand, and like you say the straight cow/horse/turkey compost is worst... is it still best to mix in the 5 assorted composts?


    Bookmark   May 6, 2008 at 3:18AM
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snibb(Salt Lake City)

Kristi...see below:
"Hmmm... why the mushroom compost? Can it work fine without the mushroom compost?" Ready for the scientific answer? Mel got a good deal on it, so, he bought it. There is no critical need for it in this mix. Its just extra.

"Also, care to talk about the tests of vermiculite vs. perlite?" First off, Perlite did work. We did the old experiment that is found in Mels original book to sprout seeds found on pg. 169. We filled margarine cups with 2 cups of either vermiculite or 2 cups of perlite or 2 cups of utelite. We then used lettuce seeds for sprouting. The vermiculite cup soaked up much more water than did either of the others. I forget the exact amount, but it was like 5 cups of water was absorbed by vermiculite, vs. 1 cup for perlite and even less than that for utelite. The did all sprout though-it took longer for the perlite adn utelite to sprout by more than a week. I love sprouting seeds this way. Two nights ago I did this same thing with snowball marigolds. I came down and looked in the cup and they had already sprouted. No more guessing on which seeds will germinate and which ones wont.

"And finally, when you say "Mel's Mix" above being still the #1, are you talking about the "Mel's Mix" that was with 5 parts of different composts?" The Mels mix we now use is peat moss, vermiculite, and this Kellogg product. No mushroom compost. It really did the best job. We looked at all the most popular brands.

"is it still best to mix in the 5 assorted composts?" Not if your using the Gardeners and Bloome compost. That will be all you need in addition to vermiculite and peat moss. I should say that I have one 4X4 bed that I originally used perlite in because I couldn't find any vermiculite at the time. That particular garden grows fine, but, I have noticed that is does need more water-noticably more than any of my other beds...hope that answers it for you...


    Bookmark   May 6, 2008 at 9:12AM
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Hey Snibb...thanks for answering. One thing left was just, what to do if you can't get gardeners n bloome? What's the second best choice compost?

    Bookmark   May 6, 2008 at 1:31PM
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snibb(Salt Lake City)

kristimama...the second place compost was from another individual that we named "Floyds Mix" and his mix was better than the other store purchased stuff, but, I don't remember what the unique ingredient was that he used. I know he had peat moss and vermiculite, but there was something else in it that smelled really sweet. Almost like oranges. All the other commercially available compost was pretty close to each other. I think you will be able to come up with something very good with peat moss, vermiculite, and whatever good compost is available. Just make sure you have the 5 different things in the compost. Once you find the vermiculite, you can probably find everything you need at one store.....let me know how you do....

    Bookmark   May 7, 2008 at 12:14AM
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jessicavanderhoff(7 Md)

Thanks for all the info-- that was really interesting to read. Are you saying that composted cow manure is not very good? What should good compost be made from, then? (I can't buy the Kellogg stuff here. Why is everything good in California??)


    Bookmark   May 7, 2008 at 4:39PM
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snibb(Salt Lake City)

jessica....I will have to go back and look at the specifics, but, the worst was turkey manure, followed by either cow, and then horse. Mel is going to have me print this all up and it may be in his new book coming out...I also wanted to say that it all worked, that is, it all came up-even the turkey manure. But, after 7 or 8 weeks, there are stark differences. Mels mix is perfect, the tallest, came up the fastest. The other stuff we looked at-even though it came up later, the plants are not as healthy. Many of them have yellow leaves-a nitrogen deficiency. Not Mels mix. Some of them are still quite a bit smaller. I did this to see if Mels mix does what it says, and I think after this we are all convinced it does. So, when people want to short circuit the soil, its important to remember that many, many things will work. That is, it will grow. But, that is where the similiarities end. Their garden plants will not be as healthy and they will not have the success that they could have with Mels mix. Lots of folks in here that use nothing but manure for their compost and they will have to do a lot of extra work to get where they could have gotten with Mels mix, most notably with chemicals and fertilizers-which you can do if you want to. Lets face it, when you are using horse manure, you are only getting two things in your compost. One-what the horse at, and two-what the horse was bedded in. Thats it. Now you know why it should be a blended compost.....

    Bookmark   May 7, 2008 at 7:04PM
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Ray_Scheel(z8b/SS31 E. TX)

I see what Snibb is saying here - buying a professionally blended and finished compost is giving better results in testing than just throwing together a hodgepodge of what is available. Based on what I've seen here of people putting beds together, too often someone ends up with "composted" bark, commercial poultry litter, and crushed dried cow chips from a feedlot that *all* needed to compost together for a while before going into production. It is not that these things are not good to make compost from, but are not good to treat *as* compost, and individually they have weaknesses that are canceled out in a blend put together by someone who has the resources to mix large lots in the right proportions for the inputs of a given batch.

Even though I primarily use mushroom compost for filling my beds (the "good deal" factor, though I let mine rest a while before planting to finish cooking, and it is a bit of a blend to start with), I always top it off with some finished homemade compost that is a very diverse blend (poultry litter from my yard birds, rabbit droppings, household compostables (food and paper), exhausted potting soil, and some yard materials (pruned branches from the immediate vicinity of the bin).

    Bookmark   May 8, 2008 at 11:00AM
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snibb(Salt Lake City) are right on the button!....

    Bookmark   May 8, 2008 at 9:04PM
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Hey Snibb.... aaaack. Can you please help me? I hope I haven't goofed big time.

We couldn't find the "Gardener's & Bloom" or Kellog-labeled product ANYWHERE last weekend. So I went to my local upscale nursery that sells a bunch of the "master nursery" products and they have something labeled "Black Forest" organic compost that seemed similar in terms of the content shown on Kellog's website.

It is basically composted fir and redwood bark fines, forest humus, worm castings, chicken manure, bat guano, and kelp meal.

The hubs did the mixing, so I didn't actually SEE the texture of the compost until today (when I bought more for top dressing) and I think it's a bit, well, "chunky." Not like the really fine black soil-textured compost I remember from my childhood compost bin. This was pretty chunky because it has a lot of forest humus in it.

Do you think I'm going to be OK? Can you describe the physical "texture" of that gardner & bloom product... is it fine and powdery, or more rought and chunky?

The next series of beds I make, I'm going to track down the Gardner & Bloom stuff... but until then I hope this other stuff will work.


    Bookmark   May 22, 2008 at 9:37PM
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snibb(Salt Lake City) will be fine with what you have...

    Bookmark   May 23, 2008 at 10:11AM
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Ray_Scheel(z8b/SS31 E. TX)

kristimama: Since I have not seen either of the two names snibb mentioned either in my "market research" (read: my inability to resist pulling into a garden center to just look around), I'm suspecting that the professionally blended composts are going to be produced regionally.

Snibb: Rather than specifying particular names, do you think the instruction to take from the testing results should be to look for the professionally blended compost that is available where the individual gardener is with some examples of balanced blends that we can gather in that are available from across the country?

    Bookmark   May 23, 2008 at 12:16PM
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Snibb, thanks. When I think of "compost" I think of the really soft black powdery compost from my parents compost bin when I was a kid. I don't think of hard chunky pieces of bark. So I panicked a little when I saw that texture on a bag labeled "compost".

Also, have to say I agree with Ray. Would it be possible to either post a picture of the Gardners & Bloom, or describe what the actual 9 ingredients are, so other people can evaluate the quality of their regionally available composts?

have a nice weekend folks!

    Bookmark   May 23, 2008 at 1:36PM
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Can someone shoot me an email with answers to the following?

What type of plywood are they using for the bottom?
What thickness
Do we drill drain holes

I am looking to build some patio boxes for my 2 and 3 year old girls who love to help me in the raised boxes in the garden. Thought I could build them their own little garden to tend to.


    Bookmark   June 4, 2008 at 2:38PM
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Snibb - I am trying to find the Gardner and Bloome that you mentioned. Is it the soil building compost?

    Bookmark   March 29, 2009 at 9:49PM
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snibb(Salt Lake City)

hey khristle...its been a year since we talked about this, but, that sounds like the right stuff. Check the ingredients and it should have like 8,9 or 10 different things in it. If it does, thats it. I think the G&Bloom product you dont want is the "soil amender." If your interested, Mels mix is now available commercially:$9.99 for 2 cu. feet. I've seen it and it is very nice...

    Bookmark   March 29, 2009 at 11:19PM
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