Haha ... This is what I started using last fall.
1 cu yard about 1200lb to 1400lb (??) bags: Bedding/potting mix (left) and course (Banana) Mix (right) I just got the Bedding mix last week. ... These are 80% pine park; 10% peat; 10% sand without fertilizer. They cost $30 & $25 per yard. So I'll let you do the math, but compared to retail store prices between $100 to $150 per 27 (1 cy ft) bags.
This is what the mixes look like.
Bedding/potting on left and 'banana mix on right. I just put up 10 flats of garden seeds in the greenhouse with the bedding mix. That's about $150 worth of plants at flat prices ($3 or $4 hundred at Walmart prices -not agian). I need to set some pepper seeds now. ... The 'banana' mix is very fast draining and holds little to no free water in the pot.
I got 3 VC plants and a Paggi last fall (Thanks Ty) shown in the 'banana' mix.
Paggi on far right and VC the 3 pots to the left. Now to what I believe were miss routed shipping by the USPS and low temps (high altitude) during shipping, the 3 plants were in poor condition when I received them. One (front pot) VC pushed 3 times but died back the the corm crown. It pushed a new pup about 10 days ago. The original growing point is dead. The other 2 VC regrew from the crown after dying back. ... The Paggi which is a difficult and temperamental banana is loving it. I lost 3 paggis last year trying to baby those in regular potting soil-perllite mix in the house. I think the greenhouse & super fast draining mix made the difference for the Paggi.
Next, after our 1st freeze of 28 F in Dec. & early Jan, I potted up in the 'banana' mix pups from my Hua Moa & a Blue Java and put into the greenhouse as backups if I loose those mats. The Blue java hasn't pushed yet, but the Hua Moa has and has a peeper showing today (enlarge photo to see).
So far I like the mixes and have no need to add additional material other than fertilizer. For fertilizer I'll ether use 10-10-10 or folar feed as needed.