Hoffmans is not available here - I use Foxfarm seed starting media. Straight. I really like it but it is pricey!
I will likely use a mix with 50 % or > Foxfarm or Happy Frog potting soil (Again pricey - but worth it). Beyond that --- not sure. But likely will mix in some perlite and builders sand. Likely some pine bark fines. Beyond that - not sure.
A dab of crushed granite chicken grit is likely in order.
I may try a couple of different mixtures and see how they do. I am gonna have a LOT or Plumerias.
And I have no idea what I will do with all of them.
I would add that I discovered a (new to me) product last summer - Earthgro potting soil. Very reasonable price and I was very pleased with it. Typically, I mixed in some perlite and some pine bark fines and that was it.