Woolly thyme (Thymus pseudolanuginosus) is a creeping thyme that makes a beautiful groundcover for hot, dry areas.
Photo by Jerry Pavia
A little plant grows over the rocky hills of the Mediterranean basin, filling the air with its savory scent and covering the ground with thick mats of tiny green leaves. The ancient Greeks called it thimari, meaning “courage.” Today, we call it thyme.
It’s easy to see why this tenacious plant impressed the Greeks. Some thymes are no more than an inch high but continue to spread outward until a hard surface bars their roots. Some make tidy mounds to a foot wide and a few inches high. They all have tiny flowers, tiny leaves and wiry stems. They look dainty. But if you have a hot, dry spot where nothing else will grow, you’ll be surprised by how tough thymes can be.
• Roast Pork Loin with Lemon, Garlic and Thyme
• Grilled Rib-Eye Steak with Red Wine and Thyme
• Baked Tilapia with Thyme and Green Olives
• Crab Chowder with Thyme
• Berries with Warm Lemon Thyme Honey
• Pan-Fried Apples with Thyme
Thymes are botanically confusing. Their tiny flowers and leaves make them a challenge to identify. Their tendency to seed around and revert makes cultivars highly unstable. Many in the trade are confused. So the best way to choose a thyme is to use your eyes and nose to find one that you like.
It is simplest to consider thymes in two groups: creeping varieties (generally originating from Thymus praecox) and bushy varieties (originating from T. vulgaris). Creeping thymes tend to be primarily ornamental. Their leaves are edible, but their shoots are so short that they’re difficult to use. Their scents often dissipate during cooking, leaving no significant taste. They have a prostrate habit and form thick mats of wiry stems covered in tiny green leaves. Quick drainage, full sun and good air circulation are the keys to success with creeping thymes. They are suitable for groundcover in hot, dry areas.
T. praecox is the most common species of creeping thyme. It grows in a mat with foliage two to three inches high. Regular T. praecox has tiny rounded shiny leaves on wiry stems. Flowers are white and shades of pale pink. T. praecox Coccineus has deeper pink flowers. ‘Pink Chintz’ is an especially vigorous selection with clean foliage and brighter salmon-pink flowers. Extra-dwarf selections of creeping thyme are also popular. T. praecox ‘Minus’ is an older compact variety with tiny blue-gray leaves and a rather lumpy, spreading habit. As with all creeping thymes, it makes an excellent filler in between pavers. T. praecox ‘Elfin’ is even smaller. It grows into a mat of gray-green foliage so tight and low that it resembles lichen. ‘Elfin’ and ‘Minus’ are highly sensitive to wet conditions, so give them a quick-draining soil. At least six hours of direct sun are essential for thymes to thrive.
Numerous varieties of T. praecox with supposed resemblances to certain scents have been identified and now circulate throughout the nursery trade. ‘Coconut’, ‘Mint’ and ‘Nutmeg’ are three that are widely available. Woolly thyme (T. pseudolanuginosus), a similar species, stands out for its hairy leaves which give the plant a soft appearance and texture.
Caraway thyme (T. herba-barona) is intermediate in habit between the creeping and mounding varieties. It doesn’t spread out in a dense flat mat, nor does it create a tidy mound. Rather, it sprawls and trails happily in between other plants and over edges of hard surfaces. Its scent has a strong odor of caraway. Overall, it’s a larger, more vigorous plant than other thymes. The leaves are wide, rounded and separate easily from the stems. Its strong aroma and flavor hold up well during cooking.
Mounding varieties are bred from T. vulgaris. Most culinary thymes are these bushy types. English and French thyme are two strains often used for cooking. English thymes have rounded, deep-green leaves. They’re often the most winter-hardy thymes, and the most tolerant of lower light and slower drainage. French thymes have narrow, pointy leaves and a sweeter flavor. They’re more susceptible to cold and wet than English thyme.
Lemon thymes (T. ×citriodorus group) are a bushy and vigorous group of mounding thymes with leaves that smell like lemon or some other citrus. There are numerous strains of regular lemon thyme, which vary in habit, leaf size and intensity of flavor and aroma. Smell them before buying. ‘Lime’ smells like its namesake citrus, although cooking destroys the flavor. Variegated lemon thymes are attractive to look at and can be used in cooking as well.
‘Silver Queen’ is the standard variegated variety, with streaky cream-edged leaves. It tends to revert back to green over time. ‘Hi Ho Silver’ is a new variety with much stronger variegation. It makes a very attractive plant, four to six inches high and a foot wide. ‘Aureus’ is the standard gold-leaf form. ‘Doone Valley’, with gold-splashed leaves, is widely available. Unfortunately, it tends to revert to green.
Gardening with Thymes
Because of their low-growing habits, thymes can be used in a wide variety of situations. Their tidy growth and clean foliage make them useful in highly visible areas. They thrive in hot, dry spots along the edges of patios and driveways, trail over ledges and retaining walls, and can fill in between pavers.
While thymes are primarily grown for their tidy habit and fragrant leaves, their flowers are also highly attractive. Their flowering season is short—a few weeks in early summer—but their light-colored blooms attract many pollinators and have a sweet, honey-like fragrance.
Thymes grow well in containers. Because of their small size, growing thymes in containers makes it possible to appreciate their intricate beauty close at hand. Wooly thyme is an excellent container specimen, with its curious fuzzy leaves. ‘Hi Ho Silver’ also makes a good pot plant, with its upright, bushy habit and heavily variegated leaves.
In areas with heavy rainfall or thick soils, growing thymes in containers may be the best way to give them the air circulation and quick drainage they require. A strawberry pot with a different variety growing out of each opening would be an excellent way to maintain a collection of thymes.
Cooking with Thymes
The most basic thyme flavor is an intense herbaceousness. Taste it, and you know you’re eating a plant. When fresh, thyme has sharp, vegetal notes supported by strong earthy tones. Dried thyme has a deeper flavor. French thyme has a sweeter note. Lemon thyme, not surprisingly, has a strong citrus fragrance and taste. The various scented thymes all smell like their namesakes, but most lose their aroma when heated.
To use thyme, simply use your fingertips to strip the leaves off the stems. They’re small enough that they should require no extra chopping. Add full sprigs of thyme to soups, broths and poaching liquids to infuse them with its aroma and flavor. Stuff handfuls of thyme inside whole roasting chickens or fish. Use a pile of thyme clippings as a bed on which to cook a pork roast or potatoes.
The vegetal taste and aroma of thyme balance the robust flavors of beef, lamb, pork and venison; it also brightens chicken and fish. Thyme pairs well with many fruits, including citrus, apples, pears and grapes, and it is the primary herb in the classic bouquet garni of French cookery. Because thyme grows wild throughout the Mediterranean basin, it is widely used as a basic herb of that region.
Thymes need nutrient-poor, well-drained soil and at least six hours of direct sun every day. Rich soils and excess water will cause them to grow lushly at first, before going lanky and rotting out in the center. Thymes can easily by shaded by larger companions. The lack of light and air circulation will also lead to rot.
Once you’ve placed and planted your thymes, you have little left to do but wait for them to establish and thrive. Avoid fertilizing thymes in the ground more than once or twice a season. If you grow thyme in a container, a monthly dose of weak fish emulsion in the usual watering will be sufficient food.
Thymes require little maintenance. They should be sheared lightly after the last spring frost to rejuvenate the plants and stimulate new growth. Cut them back heavily after flowering as well. Avoid cutting thymes back hard before a heavy frost.
Because of their shallow root systems, thymes are prone to frost heaving. Freeze and thaw damage is especially problematic when plants are growing between pavers. If the amount of soil available is small enough, the roots will freeze solid and the plant will die. Most thyme varieties are hardy to Zone 5.
Thymes tend to layer themselves around the edges. Creeping varieties are especially prone to rooting along their stems. Separate rooted stems from their parent plants and grow them in pots or a nursery bed. Thymes are rarely grown from seed.
Caleb Melchior grows unusual herbs and perennials at Sugar Creek Gardens in Kirkwood, Missouri. He is also studying for a Master of Landscape Architecture degree at Kansas State University.