Rather than a bush (like dogrose), this suggestion is a trellis crop like pepper and grapes. The seeds are found as WWS just like other seeds.
Roses take approximately the same amount of time to grow as grapes, and when harvested produce one rose and 5 rose seeds. After harvesting the original plant remains and regrows the same as pepper and grapes. The rose is a simple curio like a poppy flower. As a curio, it has good lp-per-hour, but as a downside it takes a long time to raise quality as a slow-growing trellis crop.
Special feature: The colour of the flower on the fully-grown crop depends on the ratio of the essence/sub/vitality of the plant (as red/green/blue) so larpy players can breed a rose of an exact colour with a little effort.