you might consider adding perlite to lighten your mix up. root developement doesn't mean completely rooted. in some cases it mean calluses. also different plants can take a longer or a shorter time to root. maybe they're in too much shade? do you have much rotting? if you've got the money to spend a intermittent mist prop set up will speed things along.

Some perennials (I am not familiar with the names you mentioned.) will root better if started in late fall or winter. The books and manuals don't mention this often. If you continue to have unsatisfactory results try again in December.

The simple way is to use course sand like they use in concrete.
In my rooting beds I put a 2 inch layer of small gravel and the rest course sand to make sure it drains well.
You can use this with a intermintent mist system or just place in a shady spot and keep damp.
When you use potting soil it can retain moisture and cause fungus problems at the stem
be sure and use a rooting compound.