When the heat and drought of late summer leave most perennials decimated, catmints (Nepeta spp.) stand out for their sheer survivability. No matter what summer throws at them, these carefree members of the Lamiaceae family perform reliably from June to frost with their purple, blue and white blooms and soft, often aromatic grey-green foliage.
These vigorous growers are also unfazed by cold winters, lean soils and exposure to full sun. The only conditions capable of doing them in are deep shade or poorly drained soil: as with all cats, they yearn to bask in the sun and absolutely hate wet feet.
A beautiful garden addition in their own right, catmints perform well as fillers in perennial beds, bringing cool contrasting shades of blue, mauve and violet to the hot colour scheme of summer flower beds. Many also look great in containers, tumbling over the edges of low walls or large planters, as companions for roses or as groundcover. Although catmints do spread (after all, they are members of the mint family), most do so relatively slowly.
N. x faassenii ‘Dropmore Blue’ (Zone 2)
Hybridized in Manitoba by Frank Skinner and introduced in 1932, it’s one of the best, hardiest and most versatile varieties of catmint. It has become a garden classic, much admired for its dense, mounding foliage and masses of short mauve-blue flowers. It grows 30 to 45 centimetres tall in full sun to part shade.
N. x f. ‘Six Hills Giant’ (Zone 3)
This cultivar is a robust grower (60 to 75 cm); it has fine-textured, silvery foliage and long spikes of lavender-blue flowers. Full sun and excellent drainage are musts. A similar plant, ‘Walker’s Low’ (also zone 3) has larger flowers on a more compact plant.
N. nervosa (Zone 5)
An upright plant that reaches 60 centimetres in height, its 15- to 25-centimetre-tall flower spikes are clear blue. The leaves are narrow, prominently veined and non-aromatic. While it needs full sun to part shade and is not as hardy as most catmints, it’s a good cut flower and container plant.
N. sibirica (Zone 3)
This cold-hardy native of Siberia (90 cm tall) does well in sun or part shade. The best known cultivar is brilliant blue-violet ‘Souvenir d’André Chaudron’ (syn. ‘Blue Beauty’). Underground runners are invasive. Plant in containers or divide yearly to check spread.
N. subsessilis (Zone 5)
This species has large (5-cm), trumpet-shaped, mauve flowers that fade to pink and heavily textured leaves. It’s better suited to shadier and moister sites than other Nepeta species. Grows to 75 by 40 centimetres. Divide every two to three years to keep spread in check.
N. cataria (Zone 4)
Catnip (N. cataria) is a tall, sprawling plant (90 by 45 cm) with aromatic leaves; its white or lavender summer flowers are not showy. Cats find it irresistible and may love it to death. Reseeds readily in sun or part shade. The leaves make a nice tea (if your cat doesn’t get them first).
Photo shown above: 'Walker's Low'