You've planted your catmint (Nepta spp.) in a sunny location with well-drained soil and you're waiting for it to thrive. You may have already picked some for its pleasant aroma, or as a gift for your feline friends. To keep your catmint looking its best, you need to give it ongoing care and attention.
Hardy from U.S. Department of Agriculture plant hardiness zones 3 to 8, catmint doesn't like soil that's overly fertile, so unless you have exceptionally poor soil quality as determined through a soil sample test, there's no real need to pile on the fertilizer. The National Gardening Association recommends laying down approximately 1/4 inch of compost once a year in either the spring or fall to keep your catmint well fed. A thin layer of compost allows the organic material to break down into the soil quicker.
Catmint might practically thrive on neglect, but pruning it keeps it looking its best. Prune it after the first flush of bloom -- usually in late spring -- to ensure a second blooming later in the summer, shearing the entire catmint plant back by about one third.
Catmint isn't as aggressive as its relative, catnip (Nepeta cataria, hardy from USDA zones 3 to 7), but it still can take over a garden if it isn't properly tended to. Choose a season when the catmint plant is dormant, either early spring or late fall, and divide plants about once every three to four years. Water the newly divided plants regularly until they're well established.
Catmint likes well-drained soil, and thrives in full sun -- though some cultivars like a little afternoon shade. Water young plants or recently transplanted catmint with some frequency -- about 1 inch of water each week is sufficient to ensure a healthy plant. Older catmint plants are drought tolerant and take the same amount every three to four weeks. To test if your catmint needs water, insert a finger into the soil approximately 1 inch. If the soil feels dry, water the plant.
Pests aren't a huge problem with catmint -- most of the usual garden menaces don't like the smell of catmint and avoid it. While this is good news when it comes to bugs and other creepy crawlies, you may still have trouble with other critters -- namely, cats -- although a hungry deer can also make quick work of your catmint. While catmint isn't a huge feline favorite, some of the older cultivars can entice feline visitors to roll around, eat the plant or just generally destroy it through play. For example, Six Hills Giant (Nepeta faassenii 'Six Hills Giant') is one of the most cat-attractive types of Nepeta, as well as one of the largest. Avoid damage if you have cats in your yard by erecting a dome of chicken wire to protect young or fragile plants.