Pick a sunny spot to plant your rose cuttings. Where you place your cuttings is especially important if you’re planning on growing them outdoors. Choose a spot that’s sunny but that’s not in direct sunlight — you don’t want them to dry out. Putting the rose cuttings in a pot or container is alright as well, just make sure the container is deep and wide enough for your rose cuttings to grow.
You may even wish to cut your cuttings down to 3" to 4" and double your plants, but they will be more prone to rot or dry up faster if you let the soil dry too long. The cuttings that are 6" to 8" seem to do much better, and if cuttings are even longer, the water has a longer length to travel up and down, and the cutting may end up more dehyrated with the upper part dying off. So 6" to 8" is a happy medium.
There will be disappointments along the way, when many rose seeds fail to germinate, or perhaps they do germinate, only to die several weeks later from damp-off disease. Sometimes a rose seedling will turn out to be as ugly as sin, or very sickly, and you will reluctantly have to throw it away. Other times they will be just ho-hum, or look too much like its parent, and therefore have no value. But, just when you don't expect it, you might discover that one of your rose seedlings turns out to be very special.