I will dig a hole and plant the rose and water right away.
Reduce water as weather gets cooler. You rose will come back to life next year, also look for pruning infos during winter. roses like being pruned during that time.

I believe that you'll have a better chance of rooting the bare stem if you stick it into a mixture of peat/perlite or peat/ vermiculite (1:1) which has been moistened. The container may be kept in a cool room or a basement. Rooting should be effected by springtime, but be careful not to overwater. Excess moisture spells certain death for Rose cuttings.
I wish You luck!!!