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April 2013
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You Can Grow That! April 2013: Catmint

Walker's Low catmint. Photo courtesy Stephen Still/Perennial Plant Association

Season-long flowers, attractive gray-green foliage, fragrance and a forgiving nature equal high marks when it comes to catmint in the garden.

Thirty types of catmint (Nepeta) were grown and evaluated by the Chicago Botanic Garden from 1999 to 2006 in average conditions to mimic what the perennial likely will experience in the home garden. The plants got 10 hours of summer sun a day and were planted in well-drained, slightly alkaline (7.4 pH) soil that was amended with composted leaves. They were watered as needed, but not fertilized. There was little to no insect or disease problems.

The catmints were not routinely cut back after their first flush of flowers and most of them rebounded into more blooms within a few weeks. They also are fairly drought tolerant, once established. They do well in perennials beds, as a border or in rock gardens. They attract hummingbirds, butterflies and other pollinating insects. Although a member of the mint family, most garden catmints are not considered invasive. True catmint (Nepeta cataria) can be invasive.

Catmint leaves have nepetalactone “an essential oil, which, when vaporized triggers a variety of behavioral responses in cats. The narcotic effect of catmint affects cats differently, causing them to become mellow, frisky or aggressive. Rubbing, licking or biting the leaves releases the vapors that produce the short-lived high, while eating the leaves may act as a sedative. By all accounts, true catnip, Nepeta cataria, is particularly intoxicating, but several other common catmints also attract cats,” wrote Richard G. Hawke, plant evaluation manager at the Chicago Botanic Garden.

Twenty-two of the 30 catmints evaluated rated well in flower production, robust plant habits, good health and winter hardiness. Here’s a rundown of those with excellent performance:

‘Joanna Reed,’ has lavender-blue flowers and blooms from May through late October. It has dusty-green leaves and gets 24 inches tall and 48 inches wide. It “was one of the tidiest because its stems did not flop and new growth quickly concealed the declining flower stems.”

‘Six Hills Giant’ has gray-green foliage and lavender-blue flowers that bloom from early June into October. It gets about 30 inches tall and 48 inches wide.

‘Select Blue’ has lavender flowers and dusty-green leaves. It blooms from May into September and gets about 14 inches tall and 30 inches wide.

‘Walker’s Low’ has gray-green foliage and gets about 30 inches tall, 36 inches wide. Named by the Perennial Plant Association as its 2007 plant of the year, it has lavender-blue blooms from May through late September.