THYMUS SERPYLLUM (CREEPING THYME)
SOWING PERIOD: (It is best to start the seeds indoors)
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.
SOWING TEMPERATURE: 68 F (20 C)
GERMINATION TIME: 2-3 weeks or MORE
PLANT SPACING: 6-18 in (15-50cm)
SOWING METHOD:
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.
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.