Try it. But I have the impression that he was more interested in selling you a high-margin product than in having you mix your own from things he maybe didn't have or which don't have as high a margin. I'm using a 1:1 mix of perlite and vermiculite for cuttings. I'm propagating Calif. native salvias. Growing media are like kitchen recipes: everyone has their own.

Most of the seed starter mixes that I've seen are much too fine textured. I wish that you had stuck to your original plan. ;-( You can probably improve it by adding a very large ratio of perlite.

i got a 40 pound bag of perlite... maybe 4 feet tall by 2 feet wide.. for 12 bucks .... that is a lot of perlite ...

plain peat not much difference ...

let me put it this way .. your bag of product cost 47 cents to produce ... in perlite and peat ... the rest is profit ..

if you are dabbling.. buy the premix... when you learn... and move toward needing volume.. invest the profit in your own mix ...

perlite will last 100 years in the garage if kept dry ... jsut buy an extra garbage can .. or a heavy duty contractors black garbage bag ... same with peat .. store dry .. wet .. then mix.. then use ..

ken