I am planting a succulent trough in zone 6. What would be good proportions of soilless mix, Turface, perlite, and granite grit?
In the past I have planted mini astilbe, hosta, iris, and oregano next to succulents. They didn't make it through the winter, while the succulents did. Are their soil needs too different to try growing them in the same medium?
Some of the issues you may be having include the size and shape of your trough, Its location over winter, and yes, the mix. Some of the plants you name need some organic element for vigorous growth and many "experts" include things like a bit of good garden soil, peat moss, leaf mold or other organics in various proportions. Go to the informational sections of the NARGS website for more information regarding your issues and check out the past issues of the quarterly for good advice and helpful information, it is searchable and you may want to use terms like trough, mixes,or specific growing information to the plants you are trying to grow.