Limited Supply. Penstemon 'Dark Towers' boasts glossy bronze-red foliage topped with masses of pink flowers in July and August. Tolerates high heat and humidity. Compared to 'Husker's Red' this beauty is taller and has much darker foliage which stays darker. Nice masses of large pink flowers emerge from July through August in open clusters. Dale Lindgren of University of Nebraska created this ultra-hardy form, pink flowering form.