Haven't gone to the Pro-Mix web site in a couple years. Just checked out the link to the right. Wow, they have really expanded their line! We only have the BX and the HP up here. None of the other options at all. I use a different brand starter mix called Redi-Earth Seedling & Plug Starter, put out by Sun-Gro...Which is interesting because we can no longer get the other products put out by Sun-Gro.
You'd think someone would carry all Sun-Gro or all Pro-Mix, but all the nurseries (which are outrageously priced for these products) and the big box stores all carry the same formulations...duh...just depends on how much you want to pay whether you use the nursery or Lowes.