How to Grow Creeping Thyme from Seed

Creeping thyme (Thymus serpyllum) is a perennial herb that’s winter hardy down to USDA zone 4. It has thin, fine-textured, semi-evergreen foliage and small, fragrant, flowers in shades of purple, pink and white, that appear between late spring and early summer. 

Unlike culinary thyme (Thymus vulgaris) varieties that grow into upright shrub-like shapes, creeping thyme is dense and low-growing with a sprawling vine-like growth-habit that spreads to cover the ground like a soft carpet. It is drought-tolerant and grows best in full-sun locations with well-draining soil.

Creeping thyme can be used as a culinary herb but is better suited to landscaping applications such as ground cover between patio and path stones, rock gardens and rocky slopes or a low-maintenance lawn alternative for full-sun areas that need to handle light foot traffic.  

Choosing the right Creeping Thyme Variety for your Garden

There are dozens of available thyme varieties that vary in their bloom and foliage color as well as their height and growth habit. Some creeping thyme varieties are as short as 2” tall with a dense growth habit, while others can reach 6” tall with a 12” spread or larger with a looser shape. Keep in mind the purpose you want creeping thyme to serve in your garden when choosing a variety. 

Taller varieties make good groundcovers underneath taller plants in a rock or gravel garden, whereas the shorter varieties are best suited to locations that will get light foot traffic - like in between patio or walkway stones. 

If you do want a creeping thyme that can take light foot-traffic, look for a dwarf variety, like magic carpet. Sometimes large seed bags sold as “creeping thyme” in big box stores will turn out to be taller varieties with wispy growth that don’t take foot traffic as well as the shorter, denser, varieties. 

Magic Carpet Creeping Thyme

an extremely low-growing variety of creeping thyme that tops out at about 2” tall. It has long-lasting pale purple or lavender blooms that appear in late spring to early summer. 

Red or White Creeping Thyme

‍Most creeping thymes bloom purple. But, if you want either a more subtle or a more vibrant look to your creeping thyme while it is in bloom you can also find varieties that bloom white or red (more accurately described as a bright fuchsia-pink).

Wooly Thyme

‍A dense, low-growing, thyme variety with lavender blooms and a unique pale silvery-green fuzzy foliage. A great choice if you want to add some contrasting ever-gray foliage to your garden.

What you will need to Grow Creeping Thyme from Seed

1. Creeping thyme seeds
2. Seed starting mix
3. Plastic cell trays or a soil blocker
4. Grow light

For more specifics on seed-starting supplies, read my comprehensive post on the basics of indoor seed starting. 

Tips for Success when Caring for Creeping Thyme Seedlings

Thyme has a reputation for being difficult to start from seed, largely because of the tiny size of the seeds and poor germination rates of some varieties. However, in my experience, creeping thyme is much easier to grow from seed than some other woody herbs like rosemary or sage. 

Get the Timing Right

Thyme is a slow-growing plant relative to some other plants commonly grown from seed. If you want decent-sized plants this season, be sure to start them indoors early - about 8-10 weeks before your last frost in spring. If you are late starting your creeping thyme seeds, you can continue to sow them indoors throughout the summer as long as they are ready for transplant outside at least 8-10 weeks before the first fall frost in your area.

Start your Creeping Thyme Indoors

Creeping thyme can be direct sown, but I would highly recommend starting it indoors instead. The seeds (and seedlings) are teeny tiny and they and their equally tiny root systems need to be kept moist for weeks as they germinate and as the seedlings to become established. Starting them indoors gives you better control over conditions and prevents you from having to go outside (while it’s still quite cold) multiple times a day to keep a thin layer of ground moist. 

Overseed

Some people find that thyme varieties have poor germination rates. One solution to this problem is to sow far more seeds - in your cell trays or soil blocks - than you intend to keep to be sure you end up with the number of plants you want. Thin them to 1 seedling per cell or block as soon as they are large enough to thin. 

Keep the Seeds Evenly Moist until they Germinate

Don’t let your seeds dry out. The attention needed at this stage is likely why some people have difficulty germinating thyme seeds. Check on your seeds twice a day and either bottom water them when dry or carefully mist the tops. A light sprinkle of vermiculite over the top of the seeds and a plastic humidity dome help to retain moisture without blocking the light thyme seeds need to germinate.

Start Creeping Thyme Seeds in Small Containers

Cell trays with very small cells, ¾ inch soil blocks, or shallow seed trays and wait until the plants have put on some size before potting them up to larger containers or soil blocks. Thyme seedlings stay very small for a long time. If they are started in pots or cell trays that are too large it is easy to over or under-water them as you try to keep them consistently moist over time because of the relative difference between their tiny root systems and the surrounding soil.

How to Start Creeping Thyme Seeds

1. Moisten your seed starting mix. 
2. Fill a small cell tray with the moistened growing medium. Eliminate air pockets either by tapping the tray on a flat surface or pressing the mix down, then add more mix to the cells, if necessary, so they are filled to the top. (Alternatively, use a ¾ inch soil blocker to shape your seed starting mix into soil blocks.)
3. Thyme seeds are tiny and need light to germinate. So, rather than making holes in your cell trays for each seed, overseed a thin layer of seeds on the top of each of your cell trays or blocks, making sure to use more seeds than the number of eventual plants you want.
4. Sprinkle a thin layer of fine vermiculite over the tops of each cell or block (optional but recommended) and carefully spray the tops of the cells or blocks with water. This will help to retain the moisture necessary for the seeds to germinate.
5. Cover your tray with a humidity dome or a layer of plastic wrap to help maintain humidity around the seeds and set them aside to germinate. Though the seeds need some light to germinate, it is not necessary to keep them under grow lights before germination.
6. Germination can take 2-3 weeks or more. Keep the cells consistently moist the entire time (the vermiculite and humidity domes will make this easier). Once the seeds have begun to germinate, transfer the trays or blocks under grow lights and, since thyme seedlings are so small, make sure they are kept very close to the lights - about 2 inches below.
7. Depending on the size of the cell tray or soil block you have used to start your seeds, you may eventually need to pot them up to a bigger pot or soil block before they are ready to be transplanted outside. However, thyme seedlings take a while to start growing, don’t transfer them to a larger space until they outgrow the space they are in.

How to Transplant Creeping Thyme Seedlings Outdoors

Get the Timing Right

Plan to transplant your creeping thyme seedlings outside anytime after the last frost date for your area has passed. Before transplanting, be sure to harden them off for a week or two by gradually exposing them to full sun and wind to avoid transplant shock. 

Choose a Good Location

Creeping thyme prefers full-sun and well-drained, sandy or rocky soil, though it will tolerate some light shade. Avoid full-shade locations or those with heavy or wet clay soils. Remove all weeds from the site before planting. 

Space your Plants Appropriately

Space creeping thyme seedlings between 6” and 12” apart - depending on how quickly you would like the thyme to fill in the space.

Transplant

Remove the seedlings from their pots. Gently loosen the roots if necessary. Dig holes that are just deep enough to plant the seedlings to the same depth in the ground as they were in their pots and, ideally, twice as wide. Add the seedlings to the holes and press them gently into the ground. It is not necessary to add amendments to the bottom of the planting holes. Water the seedlings well. 

For more ideas on propagating your own landscape plants, see my post on growing boxwoods from cuttings. 

Caring for Creeping Thyme after Transplanting

• Keep your creeping thyme seedlings watered regularly in their first year or two until they become established, at which point they will become more drought-resistant. 
• Your creeping thyme seedlings may not flower in their first year but you can expect blooms by the following spring. 
• Creeping thyme will grow fine in soil with poor fertility, but a top-dressing of compost and a spring application of a water-soluble fertilizer, such as fish emulsion, will produce fuller and healthier-looking plants. 
• Blooms should last for several weeks from late spring to early summer. Pruning is not strictly necessary, but you may choose to trim the plants back by ⅓-½ after the blooms have finished and then again in late winter if they are getting woody and scraggly and you would like to keep them more shapely.