By Judy Feather, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County
Veronicas are so useful and come in so many forms that gardeners may not realize these diverse plants are closely related. There are some 250 species of veronicas, also called speedwells. Many are readily available and easily grown in Colorado's climate and soils.
Some veronicas grow as ground-hugging mats while others reach 2 to 3 feet tall. Leaf color varies from glossy green to silver. Flower colors may be rose, pink, blue or white. Though flowers are often presented in spikes, some species produce blooms in small clusters. With so many species, flowering ranges from early spring through fall.
From April to June, Veronica liwanensis, or Turkish veronica, starts the flowering season. Cobalt blue flowers nearly conceal the tiny, waxy leaves. This 1- to 2- inch groundcover may appear fragile but is tough, thriving on winter drought and little summer water once established. It grows well in full sun among other plants and between paving stones and on rock walls. It is equally at home along the Front Range as it is up to 10,000 feet.
For a beautiful mid-spring display, plant V. pectinata, woolly veronica. This tough little plant is an evergreen ground cover that performs well in full sun and dry conditions. It also tolerates light shade. Woolly gray green leaves are toothed, which adds to the texture. It grows to about 4 inches tall and spreads slowly. In mid-spring it produces blue/purple flowers that last for about a month. Use it as an edging against a sidewalk or to soften the lines along a path.
In late spring, V. spicata incana, silver speedwell, can be admired for its deep blue flowers on 10-inch spikes - stunning against its gray foliage. This veronica blooms all summer with deadheading and adapts well to a variety of soils and conditions.
Look for the hybrid Veronica "Waterperry Blue." This low, trailing plant grows 4 inches high and 1 feet wide, rooting as it spreads. The rounded, bronze-tinted leaves grow on trailing stems that support loose clusters of pale blue flowers veined in deep blue.
It's mostly spring blooming, with sporadic flowering throughout summer and fall. This plant grows well in partial shade and can be grouped with hostas, coral bells and lady's mantle.
In late spring to early summer, Veronica hybrid "Sunny Border Blue" produces handsome spikes of violet-blue flowers. Blooms can be prolonged until frost with deadheading. Plants grow in compact clumps 1 to 2 feet tall and 1 foot wide. This hybrid requires regular watering.
V. alpina also can be found blooming in spring and early summer. Alpine veronica forms a 6-inch tall rosette of shiny green leaves from which foot-tall stems bear clusters of dark blue to violet flowers. The cultivar "Rosea" is pink flowered.
Summer months bring V. spicata, spiked speedwell, to center stage with its many available cultivars. The species forms rounded, 1- to 2-foot-wide clumps that send up 2-foot stems with oval, glossy green leaves topped with spikes of bright blue flowers. It has a very long season of bloom if faded flowers are removed.
Some notable cultivars of V. spicata (which are hybrids with other speedwells) include "Icicle," 15-18 inches high with white flower spikes. A clump of this white cultivar really cools down the garden.
"Nana" is dainty at only 6 inches and bears violet blue blossoms. "Red Fox" grows 15 inches tall and wide and has deep, rosy red blooms. And compact, little 8- to 10-inch "Heidekind" has rosy pink blooms. All require regular watering.
A beautiful mid-summer variety is V. longifolia. Long-leaf veronica reaches 2 feet high. Its leafy stems carry deep blue flowers that nicely complement the season's wealth of yellow flowers.
Veronicas, in general, do well in average soil with good drainage. They grow best in full sun but benefit from light afternoon shade in hot Colorado summers. Remove spent flower spikes to encourage secondary blooms. Clumps may be dug and divided in early spring or, you may increase plants from stem cuttings taken in spring and summer.
Effective companion plants for veronica are campanula (bellflower), which lends pale purple or white colors. Catananche caerulea (cupid's dart) provides blue and violet shades; Iberis sempervirens (evergreen candytuft) is an early spring, pure white accent; liatris (gayfeather) brings a fluffy purple note; phlomis supplies white and hot pink colors; and sisrinchium (blue-eyed grass) is bright blue.
Note that taxonomists rename species, and different nurseries may list the same cultivar under two or three species names. When shopping for veronicas, give attention not only to botanical names but also to descriptions of growth habit and flower color.
Photo: Judy Feather
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010