One of my favorite nurseries here in town used to sell 5 gallon roses in pots so heavy I couldn't get them out of the trunk. They potted the roses in clay soil from their property and nothing else. Those roses grew nicely. Every time I bought a rose from them, I cursed them, because I had to cut the pot off the root ball. There was no breaking up the root ball, it just had to go in the ground the way it was. I think those roses grew even better once in the ground because they were so happy to find my loamy soil. I was sorry to see that nursery close, but I was happy to buy every rose she had left on closing at a very very low price.
The bark-based potting mixes do not work for me at all. The bark in our bags is most likely pine from Texas or Georgia.
Our master gardener classes teach people to plant in regular garden soil without any amendments. I prefer to break those rules and mix compost in with the soil when planting roses. (Not with trees, though) I top dress with compost, too. Sometimes it's my own compost from my tumbler, other times it's a bag of cotton boll compost or mushroom. Horse manure shredded with alfalfa and aged 3 years is the best in my opinion. A guy near me sells it by the dump truck load but it isn't cheap. My husband bought me a truck load for my birthday one year--best gift ever!
