Should I really plant my roses in containers full of topsoil?
I've ordered some bare root David Austin roses from the company and I plan on planting them in large (22") planters that I have. I didn't see any information on their site about container planting and decided to email them to ask what type of potting mix they recommend. I explained to them the potting mix I already use (which is Al's 5:1:1 mix) and asked would this work well with the roses. The person replied that they " usually suggest a good top soil/compost blend". Also I should not add fertilizer to the mix but to wait until the roses begin to leaf out but do add The David Austin Mycorhizzal Fungi at planting.
I don't want to question the professionals but this seems to go against all I've learned about container culture as far as the soil is concerned. I've thought soil-less mixes where the standard for containers and, with the knowledge that Al has imparted, I've learned the importance of aeration in containers. Is there something I'm missing that is unique to roses that would make the suggested blend more beneficial to them than 5:1:1? Should I plant them in the topsoil mix or go with what I know?