Rose Arch. Martagon cultivar. Turk’s Cap flowers are small, downward-facing. They can produce up to 50 flowers per stem from a mature and settled bulb. Rose Arch has deep dusty rose red flowers with a few small spots that carry a light fragrance. Plants can be grown in full sun or in shade and become 5 feet in height. Clumps easily. Quite rare and an in high demand. Premium bulbs ship after October 15 – the proper planting time for northern tier gardens.