Ok I've got about 250 figs that will need to be up-potted this year into 5 gallon pots. How many yards of soil is that? This question brings all kinds of problems and even more questions.
#1. Is a 5 gallon pot 5 gallons? It's my understanding that it is more like 3.9 gallons.
#2. How many bags of pro mix in a cubic yard? 3.8 cubic ft is about 7 bags per yard.

When you do the math: 1gallon = .00495 yards, 3.9 gallons (#5 nursery pot) is about .019305 cubic yards.
In other words I think I can get 52 #5 pots out of 1 yard (7 bags) of pro mix.

Or am I completely wrong???

The next question is how do I lower that cost? I've used pine bark in my .5 gallon "first" pots, but that's not practical for the up-potting. Can I mix just regular nursery mulch in with my pro-mix? I get that for about $15.00/yd. at $35 per bag of pro mix I'm looking at $600 + 2.5 yards of mulch. (To make 5 yards of potting mix)

Grrrr. This is getting expensive. Then I have to run drip irrigation to them. That's the next issue.

I was also thinking 1/3 good topsoil, 1/3 mulch, and 1/3 promix. Any thoughts?

All I'm reading is $$$$$$$$$$$
Let us know the actual cost!  You might have to ask 'Is it worth it?'

Assuming the pots are 18" diameter and 18" tall, 25 yards

9x9x3.1415926x18=4580.4 cu in per pot

4580.4 divided by 12 cubed (1728) = 2.65 cf per pot

2.65 cf divided by 27 cf per cy = 0.1 cy per pot

0.1 cy x 250 pots = 25 cubic yards

No they are not that big. Thank God! Maybe someday. 18x18" sounds like a 15 gallon pot.

What are you up-potting FROM?  Keep in mind it will have an existing root ball, so you won't be filling an entire 5gal pot with new soil.

 ie. You won't need as much soil going from a 3gal to 5gal, as you would from a 1gal to a 5gal.

Aaron
I use horse bedding that I get free from the city arena instead of mulch .  Any stable will have plenty, most is free for the taking.  The used bedding is a combination of hay/straw, wood shavings, and of course horse biscuits.  This mixture composts very well.  Make sure you check the Ph.  This mixture can be "hot" because of the biscuits if used prior to composting so be careful.  I have been using this for almost a year.  I throw some coarse builders or better yet, river sand in as well, enough t0 make it feel "gritty" helps with drainage.  Before I added the sand I was losing stuff to root rot.

Good luck.

Horse bedding and sand? That's it? No "soil"? I think I can get that, maybe cow manure, should work the same?

I mis-read the 5 as a 15.

So I measured a 5gt pot. 11" dia x 12" tall.

5.5 x 5.5 x 3-1415926 = 95.03

x 11" (leave 1" water space) = 1045.4 ci = .61 cf = .024 cy

times 250 pots = 5.61 yards.

You can subtract the volume of the plants you are transplanting, which if they are 1g pots, means about 9/10 of a yard.

Maybe this?


http://www.metric-conversions.org/volume/us-dry-gallons-to-cubic-yards.htm