Im not an expert on mini's, but I grow a lot of them. I think that they tend to do better in the ground. Well mine do anyway. You have to fuss over them a lot more if you want to keep them in a pot. I got one for valentines day, after my son was born, and tried to grow it in a pot, by the second year it looked really bad, so I put it into the ground, and bam, it is doing well now! Its up to you, plants in pots dry out much quicker than plants in the ground. If you put it in the ground just mulch it well, and it should do fine! Hope this helps -Jessica

My This Is The Day went directly into the ground when I got it about three years ago. It has not really grown well, but it does produce a few beautifully colored blooms. Never tried it in a pot.

Just to follow-up, both of my TITD roses are in the garden and doing grand. They are blooming and growing up a storm. The brick red blooms have excellent substance and form and are lasting forever on the bush. I am glad I got them and would recommend them for anyone to grow in their garden as well.
JOhn

It is such an unusual color bloom folks always ask me what kind it is.