Their stillness made me think of qualities I try to convey in my teaching; a sense of stability, physical or mental focus, within a posture yet a simultaneous sense of ease and fluidity. The stable point itself is self-supporting rather than locked or rigid. The rose would have effortlessly flexed or stirred in a stronger wind or heavier rain.
In one of the influential text on yoga these qualities of stability/steadiness are referred to as sthira, and are balanced with sukham, comfort or ease. (Yoga Sutras of Patanjali 2.46).
The stillness of the roses also made me consider the concept of detachment/ non-attachment, referred to as vairagya in the Yoga Sutras (1.12-1.16); totally unstirred by the movement around, yet integral to the garden.