Hurdity - pot grown roses can be planted at any time of year when the soil is warm enough. Bare rooted need to go into the ground between November and March. They are usually cheaper to buy as they are younger plants. Pot grown may have been in the pot for several years, the DA one that I rescued which turned out to be a thug, was at least 10 years old by the time I resuscitated it
. Make sure that you dig out every bit of old soil where Dorothy was growing and replant into new to stop whatever disease might be lurking.
The important issue is to keep them watered, not standing in a puddle but not allowed to dry out. Roses have deep roots eventually, seeking a drink
. I usually dig out the hole and water into it, noting how long it takes for the water to soak away. Plant. Water gently from above and keep an eye for the next 9-12 months unless it's a very wet Summer.
Gardening is only as complicated as one allows it to be
........