Question
I'm kind of new at gardening & especially with roses. I bought a knock out rose "tree" last fall & planted it in a container. I live close to Charlotte, NC. I was worried about it freezing even though it should be okay to -40 degrees (that's what the label said). Someone told me it's different when it's in a container & could freeze. So, I moved it onto my screened porch during December & January. It did get a little sun most days & I watered it once a week. Now, a lot of the leaves are yellow. Is this normal? Do the leaves fall off during the winter? Would it have been okay to leave it out when some of the nights got down to 15-20 degrees? The container is a copper-coated metal one.  

Answer
Knock Out is a very hardy rose but when you put any rose into a container, it puts the roots above the ground. Soil is a good insulator and helps to keep the roots warm when the temperatures are really cold. If you want to leaves the rose tree in the garden then you can put some type of insulation around the pot such as bubble wrap, piled up soil etc. In your area that would be able that is needed. Your rose tree can easily take temperatures down to 15 and 20 degrees.
The other way to keep it through the winter is to place it in an unheated garage. During the winter, rose leaves drop off and then new ones start to grow back when the weather warms up in the spring. Because the rose doesn't have any leaves, it doesn't need any light so if the garage is dark, that is okay. Just give it  small amount of water each month such as a cup, no more because you don't want to encourage the rose to grow. All roses need a period to be dormant.
Then in the spring when the hard frosts are over, place it back in the garden. Cut the whole plant back by a third. The top should be about 18 inches across. Then it will grow back and make a nice tree for you. If you don't prune back the head, it will get very large and could either pull the whole tree over or break off the top because Knock Out roses are very vigorous. Sprinkle any type of rose fertilizer all around the top of the pot in the spring and then place some type of mulch over it as roses love cool roots and the mulch, such as bark, compost, will give them cooler roots. Don't try to keep a rose growing in the winter as it is too much work and care and the rose doesn't like it. Our houses are far too hot and dry for a rose bush. Hope this helps.