Mel's Mix-What am I doing wrong?

ageratumJune 17, 2006

I'm baffled and sure hope some of you can help me. I know this is a little tedious, but sure would appreciate your advice. I've looked through the past posts and haven't seen this problem addressed before.

I am just getting my beds set up and filling with Mel's Mix. The beds are 3x3x10, which I calculate to be 7.5 cu.ft. per bed. For convenience, I rounded to 8 cu.ft. and figured how much of each ingredient I needed to fill 3 of the beds. Of course, it came to 8 cu. ft. so I bought 2 bags of vermiculite (4 cu ft each), 8 bags of compost (1 cu ft each), and 1 bale of peat moss (3.9 cu ft which, as I understand it, should expand to 8 cu ft). Only - here's my problem - the mix only filled 2 beds! There was enough left over for maybe 1/4 of a third bed, but certainly not enough to fill it!

Where did I go wrong? Did I make a math error? Has anyone else experienced this? Except for the expense of it, I really wouldn't be too concerned, but I find I'm spending more than I want to on this project! I know I'll be embarrassed if I've made some glaring error, but tell me anyway!

Thanks in advance,


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ageratum, unless I'm missing something your math is correct. I haven't made up my mix yet and am curious as to how this worked out. My beds are 4x8x8" which figures 21.33 cubic feet, 7.11cf per ingredient. I'm going with 8cf per ingredient. Vermiculite doesn't compress unless you crush it and the compost is pretty much stable in volume. I would say the only none stable ingredient (volume-wise) would be the peat moss. Maybe it expands to 8cf while it is still dry, but compresses some once wetted...???

I've been wondering about the volume in a processed bag of compost...the ones I've seen basically state their weight....usually 40 or 50 pounds. A tidbit from "How to Grow More Vegetables" states that one cubic foot equals 1.5 five-gallon buckets, and one five-gallon bucket equals .67 cubic feet.

I'm curious as to others experience with the final volume of Mel's Mix that they get.


    Bookmark   June 17, 2006 at 8:43PM
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I, too experience a bit of a shortage in my calculations, but summed it up to too much wine while filling the bed, or figuring the total.

    Bookmark   June 17, 2006 at 9:18PM
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I have two possible explanations for your observations of the final mix volume. First, when I mix ingredients like these together, I usually find that the final volume is less than the sum of the volumes of the input ingredients. Much of the volume change I attribute to the fact that the vermiculite has lots of air spaces when packed by itself. When peat and compost are mixed in, they occupy some of those air spaces, and do not bulk up the mix by their volume in the bag. Secondly, I find that compressed bags of peat do not provide double their bulk when opened, fluffed and then wet. I usually find that they contribute significantly less than double their bulk to the final mix.


    Bookmark   June 21, 2006 at 6:49AM
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Ray_Scheel(z8b/SS31 E. TX)

Ditto Renais on the reasons, I'd say it was a combination of the two factors. I've never actually experienced it since I've never measured that close, my beds are mostly compost withthe other parts tossed in as available, but I have bulk compost readily available and a nearly infinite supply of leaf mold for the raking out in the woods. However, when I have provided volume figures here in the past based on supplied bed dimensions I usually gave a number that was a 10-20% overage for the total volume involved and its usually worked out. (FWIW, an extra 10-15% is kind of a construction/landscaping rule on purchasing base materials to make sure you have enough to finish all from the same batch.)

    Bookmark   June 22, 2006 at 1:04PM
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bluejean(z6 OH)

I started out the season with full beds (24inches high). Things have settled, or maybe things are being broken down more, but anyways- the volume has dropped over 6 inches. And yes- I already checked- nothing is being washed out anywhere. I anticipate adding more Organic matter come fall and then again in early spring. Hopefully then everything will have had a chance to settle before I plant again.

    Bookmark   June 22, 2006 at 2:18PM
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Thanks for your ideas on my problem. I must admit I'm relieved to have my math verified - I mean, I used to teach high school math! Since I'm a teetotaler, I know my shortage has nothing to do with swampboogiequeen's wine - even though it sounds like she's having a lot more fun with this than I am! So, I'm just gonna adopt the "peat & compost fill up the air pockets" theory and forget about it. I've planted squash, cucumbers, peppers and tomatoes. Everything seems to be growing great. Now, I need to fill 4 more beds (I'm using the 3x3 Grow Beds from Gardeners' Supply)and plant beans, peas, etc. At least I now know how much 'stuff' to buy to fill the boxes. Thanks for your input.

    Bookmark   June 23, 2006 at 1:40PM
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WOW!!!! I know this is AN OLD post and I'm sure you guys are good gardeners BUT you all REALLY SUCK at math. Maybe gardening does that to you! I can't believe Ageratum was a MATH TEACHER! No wonder verified German research has proved this generation is less educated than the last! A 3inch by 3inch by 10inch bed would prove the numerical math right but the UNITS ARE WRONG! LOOK it is not a 3inches by 3foot by 10 foot bed. It is a 3 foot by 10 foot bed which there are three of! Each bed has to be 6 inches deep, not 3 inches deep! A 3 foot by 10 foot bed if 12 inches deep would require 30 cubic feet. But in Mel's Mix it is supposed to be 6 inches deep so halve that and you get 15 cubic feet per plot! So Ageratum, you need 5 cubic feet of Verm, Comp, and Peat. Times that by 3 and you get 15 cubic feet for each! NOT 7.5!!!!

    Bookmark   January 1, 2009 at 11:01PM
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Heh, at first glance I was agreeing with you, but I'm fairly sure the original poster was saying a 3 foot long by 3 foot wide by 10 inches deep bed. If you work with those dimensions, you will indeed come up with the same feet. Be wary of those goofy German researchers. Just my opinion.

    Bookmark   January 2, 2009 at 1:46AM
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korney19(z6a Buffalo, NY)

I know the thread is old but...

3.8 cu ft compressed bales "uncompress" to about 6 cu ft.

    Bookmark   May 10, 2010 at 11:09PM
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