|'Waltham' has a dense, mounding habit, to 3 feet tall and wide, and bears an abundance of showy, vivid, pink flowers beginning in mid-April. Leaf spotting occurs when exposed to full sun. The 'P.J.M.' group of rhododendrons are smaller, growing to a height of 3 to 6 feet tall. Form is rounded and foliage is leathery and dark green.
One of the reasons the 'P.J.M.' group is such a heavy flowerer is that the plant does not set seed. An excellent rhododendron for the New England states. This rhododendron is the result of a cross between R. carolinianum and R. ferrugineum. It was first developed by Dr. Robert Ticknor.