Volume/Ratio Calculating Al's 5-1-1 Mix

11 years ago

After a lot of reading I decided to use the 5-1-1 mix for my container veg. I am lucky enough to have a resource for pine bark fines relatively local, so I bought several bags that are 2 cu ft each.

I decided I needed a "big batch," so I used a bag of the pine bark fines, and then measured out 5 gal each of peat and perlite using a 1 gal bucket. The lime and CRF were also measured that way - I eyeballed about 1/4 of the 1 gal bucket for the two together.

I mixed it all up, potted my plants, and then got out a 20 gal smart pot for my blueberry plant, which is in need of repotting into something larger (I would have gone with the gritty mix, but wanted to get it in something for a year while I tracked down ingredients). I figured since I didn't need a "big batch" I would just scoop using the 1 gal bucket and do 10 scoops of the pine bark, 2 scoops each of the peat and perlite, and then add my gypsum and CRF.

As I scooped the pine bark, I realized that I was going to empty the bag - which had spilled a little, but it still had about 1.75 cu feet left in it - to make this batch. I started to wonder how that was possible - if I was using nearly the same amount of pine bark, how would I only be using 2 gal each of perlite and peat rather than nearly 5 gal each?

What did I do wrong? Is there something going on with volume and ratios and such? Did I make a mistake by scooping the pine fines? The last time I took math was calculus, and that was almost a decade ago.

I have enough of each part that I can easily do several more "big batches." I hate to waste the ingredients, but if I screwed up on the plants I already potted I'd rather just eat the loss and get it right.

To summarize, without discussing the lime/CRF -

The big batch I made has:

-1 bag stating 2 cu ft pine bark fines

-5 scooped gallons peat

-5 scooped gallons perlite

The smaller batch I made has:

-10 scooped gallons pine bark fines, which seems to be roughly 1.75 cu ft pine bark fines

-2 scooped gallons peat

-2 scooped gallons perlite

Here are the provided measures so no one has to go searching. Thank you Al for such great, detailed reading!

The 5:1:1 mix:

5 parts pine bark fines (partially composted fines are best)

1 part sphagnum peat (not reed or sedge peat please)

1-2 parts perlite

garden lime (or gypsum in some cases)

controlled release fertilizer (if preferred)

Big batch:

2-3 cu ft pine bark fines

5 gallons peat

5 gallons perlite

2 cups dolomitic (garden) lime (or gypsum in some cases)

2 cups CRF (if preferred)

...I'm sure this can be answered in a couple of sentences, so I apologize in advance for the long-wind post!

Comments (5)

Ohiofem 6a/5b Southwest Ohio
11 years ago
A cubic foot is about 7.5 gallons. So a 2 cf bag of bark is 15 gallons, and therefore your "big batch" mix was actually 3-1-1. Then you say you added one quarter of a gallon of lime and crf. One quarter of a gallon is a quart, or 32 ounces, or 64 tablespoons. You added 32 tablespoons each of CRF and lime to 25 gallons of mix, which is 7 tablespoons too much. I would reccomend adding 7-10 gallons of bark to that mix to match the original 5-1-1 formula.
Buckeye85
Original Author
11 years ago
Thank you so much! A couple of follow ups to make sure I'm getting it right:

1) The reason I am over by 7 tablespoons is because the total volume of the mixture is 7-10 gallons short, but adding more pine bark will make my 32 tablespoons (4 cups total) correct?

2) Does this mean that the recommendation to use 2-3 cu ft is always going to be 3? Is there some reason to use less if it is a 3-1-1 instead of a 5-1-1? Not trying to be obtuse, just wondering why it says what it does.

3) Is it bad practice to un-pot the plants I just potted yesterday and add the pine bark to that and re-pot them? I am a novice so I have no idea if this is a huge no or not. I can easily make a new batch, but I hate to be unnecessarily wasteful.

Thank you again, from another Ohioan!
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Ohiofem 6a/5b Southwest Ohio
11 years ago
I can't speak for Al. I hope he or someone else who has used this mix for a while will chime in. I always followed the advice to add one tablespoon of lime per gallon of mix and I prefer to measure five gallons of bark to three each of perlite and peat. My formula was closer to what he describes as a small batch:

Small batch:
3 gallons pine bark
1/2 gallon peat
1/2 gallon perlite
4 tbsp lime (or gypsum in some cases)
1/4 cup CRF (if preferred)

You will notice this is actually 6-1-1. Al has said many times that these formulas are really more of a general concept. I suspect he didn't want new gardeners to get hung up on making exact formulas. I don't think you should repot anything you just put into the mix you made. It is fine the way it is. I was mainly trying to explain why there was a difference in your measurements between the two batches.
Buckeye85
Original Author
11 years ago
I wanted to follow-up and thank you again. The plants are growing like crazy (without repotting) and seem to be thriving, so everything did work out in the end. Sometimes I think I get a little bit of the paralysis by analysis syndrome!
Ohiofem 6a/5b Southwest Ohio
11 years ago
Congratulations! My garden is thriving on 5-1-1 too. It's all about good drainage.