Although rose breeders are getting closer every year, there is no such thing as a truly blue rose. The next best thing are roses such as Blueberry Hill, Blue Girl, or Blue Nile, in interesting shades of silver, lavender, or deep purple that can sometimes appear almost blue. While the idea of growing a rose of any color may seem challenging, roses are actually sturdy plants that will be hale and hearty with a minimal amount of care.
Dig hole slightly deeper than the height of the rose's container, and about twice as wide. Add a small amount of slow-release fertilizer to the bottom of the hole, according to the manufacturer's instructions. Follow the fertilizer with a shovelful of compost.
Remove the rose carefully from the container, and put the rose in the hole. Look for the soil line on the container, and plant the rose so the top of the soil will be at the same level. Adjust the soil in the bottom of the hole, if necessary.
Fill the hole halfway, alternating layers of soil and compost. Add a small handful of fertilizer, and fill the hole with water. When the water has drained, fill the remainder of the hole with soil, and water again.
Spread 2 to 3 inches of organic mulch around the base of the plant, but leave a few inches around the trunk so the mulch won't pile up against it. Mulch will enrich the soil while it controls weeds and conserves moisture.
Water the rose bush when the top 3 inches of soil are dry, and then water it slowly and deeply. Always water at the base of the plant, and don't splash the leaves.
Deadhead, or clip off blossoms as soon as they fade. This will direct the bush's energy to developing new blossoms.
Feed the rose bush a good quality rose fertilizer monthly between spring and the end of August. Fertilizing in fall and winter will create new growth that put the bush in danger of cold weather damage.
Protect the rose bush for winter. Mound soil up loosely around the base of the plant, and wait for the ground to freeze. When it does, create a mound of mulch around the bottom 6 to 8 inches of the bush. If your climate is extremely cold, or if the rose is exposed to chilly wind, circle the bush with wire fencing, and fill the fencing with mulch such as straw or dry leaves. Remove the mulch in spring.
Prune the rose bush in early spring, before it develops new growth. Remove any dead canes, and any branches that look weak or spindly, as well as any branches that are growing towards the middle of the plant, or that are crossing other branches.