The best time to plant roses will be in the spring when the ground is thawed. There is not a specific temperature at when to plant roses as long as it is not the freezing cold winter temperatures when the soil is frozen. Roses require at least six hours of sun light. It is best to plan the area before even planting the roses. They do not need an over exposure to the sun or they can get sun burned. You want them in just the perfect area where they will receive about four to six hours of sun light daily. If you live in a shady area, then planting them where they get at least four hours of direct sun will be fine.
Roses cannot tolerate extreme heat or extreme cold. They will respond to both of those conditions by not growing well. The nurseries have plants that are recommended for your specific area temperatures and can advise you on which ones are more tolerant. Most roses bloom their best in the early summer and in the fall because that is when the temperatures are very moderate. If you live in the south, then it is best to plant your roses in a place where they will receive the morning sun. This will give them the best results. In colder climate areas, most of the roses will be able to grow without winter protection. It is not wise to plant your rose in a part of your yard where cold air is accumulated (like low areas). There are roses that are hardy in the colder climates such as the hybrid perpetual and the eglantine rose. The damask, gallica, alba, rugosa, shrub and moss roses are also hardy roses. Winter protection will be necessary for less hardy roses. You can mound soil up over their crown to a depth of five inches to protect them.
If you live in a colder area, you should plant your roses a little deeper and keep in contact with your local nursery. If you buy the roses potted, they will need to be planted about an inch deeper than their actual potted level. If the temperature has fallen below ten degrees Fahrenheit, roses can still actually grow healthy if you care for them properly. The last fertilization in zone 7 and colder should be by the 15th of August to stop new rose canes from emerging. The new rose canes will not survive the winter temperatures.
If you live in hotter more desert climates, the late fall and early spring temperatures will be the best for rose planting. Roses will need to have an even supply of moisture distributed. Approximately an inch of moisture per week should be sufficient. If you are not able to water your roses at least weekly and would rather then depend on the rain, it is best to plant drought tolerant rose varieties or a tougher shrub rose in the spring and summer. Choose an area in your yard that is easily accessible. Feed and care for your plants efficiently, and consult with your local nursery for the season you are planting your roses in to ensure you have the right temperature-tolerant roses.