University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article


COOL CATMINTS

Dr. Leonard Perry, Extension Professor
University of Vermont
 
 
There are many colorful catmints to choose for gardens, some more attractive to cats than others. These plants provide easy culture, many flowers in cool blue and lavender colors, a long season of bloom, and attractive leaves.

As the name indicates, this genus of perennials (Nepeta) is in the mint family along with such relatives as the giant hyssop (Agastache), bee balm (Monarda), and lamb’s ears (Stachys).  In addition to mint, many herbs also are in this family including lavender, rosemary, and thyme.  All share traits of two-lipped flowers, square stems, opposite leaves, and often fragrant oils.
           
It is the oil “nepetalactone” which causes various behaviors in cats, depending on the cultivar (cultivated variety), the cat, and its use.  Rubbing leaves releases vapors that produce a short-lived high in cats, while eating leaves can make them sleepy.  The true catmint (N. cataria) is the most intoxicating to felines.
           
Catmints are best grown in full sun and well-drained soils.  Once established, some are drought tolerant.  One species is an exception (N. subsessilis), being adapted to part shade and moist soils.  Their main problem is wet soils which cause poor health, and too much fertilizer which causes floppy stems.  If plants become unattractive after bloom, shear back by about two-thirds to promote new lush growth.  Cutting back taller cultivars by about one half in early summer may delay flowering somewhat, but will promote lower and more bushy growth.

Depending on selection, catmints can be used in borders, herb gardens, rock gardens, massed, as edging, or as groundcovers.  A great place to use them is to soften edges of paved surfaces such as walks.  Their lavender to blue flowers combine well with yarrows, hardy geraniums, sages, ornamental grasses, black-eyed Susan, coneflowers, and Shasta daisies.  They are good for pollinators such as bees, butterflies, and hummingbirds.
           
A study at the Chicago Botanic Garden, similar in climate to much of central New England (USDA zone 5b), compared over 30 selections of catmint for at least four years each.    Four rated best for vigor, flowering, hardiness, and freedom from problems.  These didn’t need shearing to rejuvenate. 
          
‘Joanna Reed’ blooms from mid May to late October in Chicago, with lavender-blue flowers.  New growth of dusty green leaves quickly hides the declining flower stems.  It forms a tidy mound 24 inches high and 48 inches wide.  Similar, only slight higher, was another top rated cultivar ‘Six Hills Giant’.  This one has been around for many years and is commonly found.
           
‘Select Blue’ (N. x faassenii)  is similar to the first two above, only shorter (14 inches) and less tall (30 inches).  It has a shorter bloom period, but still quite long in Chicago from late May to mid September.  The flowers are a bit darker than the species, but still lavender.
           
‘Walker’s Low’ (N. racemosa) was the other top rated catmint, and is not low as its name implies.  Instead, it is named for a garden in Ireland.  Its height is similar to ‘Six Hills Giant’.  It bloomed in Chicago from mid May to late September.  This cultivar also holds the honor of being the 2007 Perennial Plant of the Year of the Perennial Plant Association.
           
If you can’t find these four selections, don’t worry as 22 of the 30 catmints in this trial rated highly. One of these is the popular ‘Souvenir d’Andre Chaudron’ (N. sibirica).  This large plant, reaching three feet wide and high, benefits from pruning back in early summer.  While the top four rated selections all had dusty or gray-green leaves, this one has green leaves.  It has a long, but shorter, bloom period more just during summer.
           
For pink flowers, look for the cultivar ‘Sweet Dreams’ (N. subsessilis), or ‘Dawn to Dusk’ (N. grandiflora) for pale pink flowers. 
            
Full details on the catmints, and other perennials, at the Chicago Botanic Gardens trials can be found online (http://www.chicagobotanic.org/downloads/planteval_notes/).

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