If you have ever seen a cat lost in the ecstasy of rolling around in a plant of catmint, you will know just how attractive these plants are to them. You might then think that is all they are good for, and perhaps lacking a cat, who bother growing one? If all you have seen in the fairly unassuming ‘true’ catmint, you might be right, but that plant has some enchanting sisters, mostly less attractive to cats, but way more attractive to gardeners. The unique clouds of gray and blue they create in your garden star in all the top photo spreads and garden books, and no wonder. These plants are the perfect balancing act for other flowers, going with all colors and adding a wonderful unifying look. Planted alone they are just as great, so let’s explore the catmints, and see just how great they are, and how easy they are to grow.
The True Catmint
It’s common to think that all catmints are equally appealing to your favorite feline friend, but that’s not true. If your main interest is to turn your cat into a melting mound of ecstasy, then you need the real thing. While they often take an interest in the catmints we will look at for gardens, they rarely roll in them, or take such obvious pleasure in their aroma. That ‘real thing’ is a plant called Nepeta cataria. It grows naturally over a wide area, all the way from southern Europe, through the Middle East and Central Asia and into western China. With cultivation and human movement, today it can be found growing wild across all of Europe, in parts of America and also in New Zealand. Sometimes this plant is called ‘catnip’, and it would be great to use this name just for this plant, and keep ‘catmint’ for the more ornamental garden plants we talk about later.
The Catnip Plant
Catnip is a perennial plant, sprouting from the roots each spring, and growing between 12 and 18 inches tall, forming a sprawling mound of stems. The leaves are wedge-shaped, with scalloped edges, and they are a dusky green color, with a soft, velvety surface. In summer clusters of small pinky-white flowers grow at the ends of the stems. These are fragrant, but it is the leaves and whole plant that has the distinctive smell that drives cats wild. This smell is from a chemical called nepetalactone. This is a terpenoid, a big group of organic chemicals responsible for many plant aromas, from cinnamon to ginger, and mint, eucalyptus and mustard. Nepetalactone has no effect on young kittens, but it affects about two-thirds of adult cats, causing them to paw it, roll in it, shake their heads, lick themselves, and often sprawl out in a state of euphoria or ecstasy. Lions and leopards are also affected, but not tigers, bobcats or cougars. About one-third of cats are not affected, or only mildly. This seems to be a genetic, inherited difference, and if your cat doesn’t respond, try another attractive garden plant called Valerian (Valeriana officinalis). Yes, catnip works on the same receptors that opioids work on in humans, so it’s no wonder they love it so much.
But enough of cats. Let’s turn to the plants that gardeners call catmints. Like catnip they are in the group (genus) called Nepeta. This is a large group, with about 250 species found almost the way around the north of the globe, from Europe to Asia, and in northern Africa. Only a handful of species are grown in gardens, and some hybrids. The foliage colors varies from green to silver, and most garden forms have silvery-gray foliage, which is more attractive, and ‘useful’, than the green of catnip. Even more important, garden catmints have flowers in different shades of blue, from dark sky-blue to deep purple, depending on the variety. Blue is a relatively rare color in the garden, and it is unique in its ability to unify all other colors, and to give a special ‘flavor’ to your beds and your garden generally. Most gardeners covet blue flowers, and try hard to have them among their plantings. The easy-to-grow catmints are a terrific way to introduce bluwa, along with the equally valuable silver-gray tones, which also unify, and act as a backdrop for, your other colors.
Before 1930 the only catmints grown were natural species, and they were not grown at all much before then. They aren’t even mentioned by the famous Mrs. Beeton in her gardening manuals from the 19th century. It was probably the craze for rock gardens that began at the end of that century, and continued into the 1930s, when they were first grown. Just a handful of species were being cultivated in replicas of the mountain ranges popular with hikers – another craze of the times. Today we grow them extensively in beds of perennial plants, but even the famous Gertrude Jekyll, from the very early 20th century, only mentions one (Nepeta racemosa), in passing, and hardly ever used it.
As so often happens in gardening, it was hybrids, with their toughness and vigor compared to natural species (often true, but not always) that brought them into wider use. The two most common species in gardens were the Eastern Catmint, from Turkey and Iran, with vibrant blue flowers, called Nepeta racemosa, once called N. mussinii, Another was Nepeta nepetella, the lesser catmint, a rare herb with small blue-violet flowers and green leaves, from Italy and southern Europe. In the 1930s, at a nursery in the Netherlands, J.H. Faassen either deliberately or accidentally crossed these two together. The resulting hybrid, called Nepeta x faassenii, has become the dominant garden catmint, and it has given rise to several varieties that vary in size and flower color.
Known for their silver-gray toned leaves and powerful flower colors, these vigorous plant grow between 2 and 3 feet tall and wide, and vary in flower color from the rich lavender blue of ‘Walker’s Low’ to the brighter blue of ‘Six Hill’s Giant’. Notice that ‘Walker’s Low’ is not particularly low, but named after a tag that it was collected in a low part of Mrs. Walker’s garden in Ireland. Neither is ‘Six Hill’s Giant’ significantly larger than any of the others!
Another hybrid was created a few years earlier, in Canada, which remains the best for cold areas. Called ‘Dropmore Hybrid’, or Dropmore Blue Catmint, it also has the more tender Eastern Catmint as one parent, but this time the other is a very cold-resistant species called Nepeta ucranica, from the Ukraine, was used. The plant is named after the small town it was created in – Dropmore, Manitoba. In the 1920s the town was home to a breeding station of the Manitoba Department of Agriculture and Conservation. Dr. Frank L. Skinner was the breeder, and his interest was in creating garden plants for the chilly prairie towns and villages. It is often wrongly listed as a variety of Faassen’s catmint.
Choosing and Growing Catmints
From a gardening viewpoint, it doesn’t matter much which ones you grow, although gardeners in cold areas should definitely try to find ‘Dropmore Hybrid’. They all need well-drained soil and lots of sun. You can keep catmints a little more compact by taking out the tips of the stems when they are just a few inches tall. This ‘pinching out’ encourages lower branching and a bushier plant. Don’t over-feed or they may become floppy, and trim after the first flush of flowers – you will often get a second, smaller one. Plant them in the front of your beds, perhaps spilling out over a terrace or driveway, or grow them on slopes and among rocks.
Most of all, admire them for their charm and beauty, fitting perfectly into gardens of every style, with all other plants. And don’t forget to grow a plant of catnip somewhere, just for puss.