Plantsman Graham Stuart Thomas observed (Perennial Garden Plants 1976,1990) that Polemonium caeruleum, the old garden standard Jacob’s Ladder, has been cultivated since Roman days. After all those centuries, something new can now be seen in Jacob’s Ladder cultivars as new hybrids have been introduced to the market over the past few years.
Pictured above is Polemonium reptans ‘Stairway to Heaven’, which was introduced by the New England Wildflower Society. P. reptans is known as Creeping Jacob’s Ladder, and forms a loose mound. It is arguably at its most attractive early in the spring, when the new leaves bear a beautiful rosy flush.
The paired leaflets, climbing up the stem, are the source of the rather fanciful common name of Jacob’s Ladder. ‘Stairway to Heaven’ produces small blue flowers that appear around the end of May here. By then, the leaves have taken on their summer colours of grey-green outlined with cream margins.
P. reptans ‘Touch of Class’, below, is a sport of ‘Stairway to Heaven’. It features a tighter mounding habit and larger leaves, with a narrow white border. It was introduced by Sunny Border Nurseries of Connecticut. Polemonium reptans is native to Eastern North America.
Unlike these two variegated cultivars, Polemonium boreale ‘Heavenly Habit’ has ferny green leaves, but its flowers are more striking than those of its variegated cousins. Below, ‘Heavenly Habit’ blooms beside Corydalis ‘Wildside Blue’.
Here’s a closer look at the showy flowers of ‘Heavenly Habit’. P. boreale, or arctic polemonium, has been variously described as a hybrid with P. reptans or as a variety of P. caeruleum. All of my polemoniums grow in partly shaded locations where they are protected from the full blast of the hot afternoon sun.
My favorite is probably Polemonium caeruleum ‘Brise d’Anjou’, a cultivar of the old European and Asian standard P. caeruleum. ‘Brise d’Anjou’ or Breeze of Anjou, was a chance discovery at a nursery in France and was introduced by Blooms of Bressingham. I love the goldy shade of the variegated leaves.
Maybe the best thing about Jacob’s Ladders is the way, after checking on them in the garden, they leave me humming that old spiritual “We are…climb-ing…Jacob’s…La-a-dder…” as I continue my stroll through the garden.