Cubic inch to gallon conversion

[TomatoDon]

I have a Rubbermaid Roughneck container, much like what Raybo uses for his self watering earth tainers. The dimensions say: 24 x 18.5 x 20 inches, and 24 gallon and/or 90.8 liters.

My math shows 24 x 18.5 x 20 = 8880 cubic inches. The conversion from cubic inches to gallons shows: Answer: 8880 in³ = 38.4415 gal(US Liq) OR 38 gal(US Liq) and 3.53 pt (US Liq) and...Answer: 8880 in³ = 33.0354 gal(US Dry)


I don't understand where they get the in3. Is there an error, and if not, what is the correct answer? I would assume that Rubbermaid is meticulous in getting their measurements correct. So I either have a 24 gallon container, or a 38.44 gallon container, or a 33.03 gallon container.

Which is it?

DS

[tam91]

Hmmm. Don't the container's sides slope some? (mine do) And have rounded corners? That could take away some volume.

Sit out there with a gallon jug and a hose, and see how many it takes?

My best guess is that Rubbermaid is right.

[tam91]

Actually, the 33 or 38 is apparently the difference between liquid or dry gallons. Why? I have no clue. But this site shows a difference between the two:

http://www.metric-conversions.org/vo...to-gallons.htm

[TomatoDon]

Hi Tam,

These are pretty squared up but I'm just that just a minor taper would add up to several gallons. Rubbermaid probably got it right, but I tried to do the math and you saw what I came up with. But 24 gallons is a good size regardless.

Thanks!

Don

[tam91]

Well I came up with the same as you, with the difference being the liquid/dry thing. Which leaves me totally confused.

That is a good size though - I'm growing my tomatoes (one each) in 18-gallon containers, just dirt - not self-watering, and they seem quite happy.

[TomatoDon]

I assume you tried the gallon jug technique to see how many gallons it took to fill your container.

A 15 gallon size seems to be the magic number. I notice a lot of our most serious growers use a 10-15 gallon container, rarely less than 7 and rarely more than 15, except of course the Rubbermaid totes and such with the self watering conversion. I try to use the biggest size I can handle instead of the smallest size the plant can produce in. I used to grow thousands of nursery trees and I always like containers 20 gallons and up. We always watered by hand or sprinkler and I'm just so used to that, that I never changed.

I transplanted two rooted cuttings today and was surprised how cool the soil mix was just a few inches deep.

DS

[tam91]

Haha no I left that for you I just believed the manufacturer (actually I have the $4 ones from K-Mart, some I even got for around $3 on sale). They've held up for 2 years now perfectly, so why not I guess. Nice light color too. It just seemed to me that the big plants would like a big pot, and that's about as big as I can handle. Plus, the price was right.

I did go through some hand-wringing calculations figuring out how much soil etc. to buy though.

[TomatoDon]

Did you sprinkle in some dear ole Mother Earth?

[maf]

For the similar containers they sell in the UK, the manufacturers always give the external dimensions which includes rims, lids, handles and so on. That could explain it, but I don't know if you've already got out the tape measure and checked out this possibility.

(I admit I use the jug and measure the volume sometimes)

[tam91]

My dear old mother earth contains Juglone (walnut trees) hence the need for containers (grr). So no, no mother earth added.

I'll have to look at the fancier mixes - but I used 1/3 peat, 1/3 composted horse manure, and 1/3 topsoil. Seems to be working pretty well.

[TomatoDon]

Another legitimate reason why container growing is sometimes a true necessity.

Do you do anything to insulate the containers and/or block the sun from hitting directly on them?

[tam91]

Actually no, I don't do anything special.

However, looking from the south, there are pepper plants in front of them that provide some shade. Also, my rows run north-south (with the containers end-to-end), so each container/tomato probably shades the one behind him.

The k-mart containers are fairly lightweight, and are a light beige in color - so that probably helps too.

We've had a horrid hot summer, and they don't seem to have suffered.

btw - as far as the soil mix - I'm probably having beginners luck. Read it somewhere, and it seems to work for me. No clue if it's technically correct though.

[TomatoDon]

If it works, it works. Sounds like you are doing fine and don't need to fix anything.

Do you notice and obvious taste difference in container grown vs earth grown? If you've been at your present location a while I'm sure you've grown in containers a long time due to the walnut trees.

[tam91]

Actually, I've only gardened a few years here. The first year I discovered the walnut trees (by all of the tomatoes suddenly dying). Then, containers for the past few years.

At my previous home, some years ago, I had tomatoes in the ground - but I only had hybrids, I just discovered heirlooms a few years ago.

The only one I can directly compare is Black Cherry - it's the only one that didn't die from the walnut trees when in the ground, and I've grown it in the containers since. To me, it tastes the same.

I also got a few tomatoes from a local organic farmer a few years ago, he of course is growing in the ground - can't say his tasted better than mine, but of course they weren't the same varieties.

So on my very limited data, I think they taste as good from the containers. Most of my fruit doesn't get huge though, but I don't have the best sun either. I have had a few "whoppers" though.