The Rose is a Vanilla item that can be be found on grass or by using Bonemeal on a Grass Block. Roses are rarer than Dandelions. The crafting uses for the Rose in Tekkit are for making Rose Red dye and the Harvest Goddess Band.
In Cross Breeding, Roses are considered a Tier 2 plant (Tiers range from 1-8).
When Rose Crops are harvested there is a chance for them to drop Rose Red and/or a Rose Seed Bag.