It’s wonderful to have fresh thyme at hand, especially through the winter. But it can be hard to start from seed. Even if you can get the teeny seeds to sprout, the seedlings often turn yellow and die a few days later. After a lot of experiments, we found an approach that works pretty reliably.
The key seems to be not getting the new leaves of the seedlings wet, and managing moisture carefully overall. All the watering is going to be from the bottom. You’ll also need a sunny, warm spot. Colorado direct sun in the summertime is too strong, but a bright south window in the winter or a partly shaded patio in the summer works.
You will need a shallow container that has lots of drainage at the bottom, no more than about 2 inches high. We still have some plastic seed starter trays from before we started avoiding plastic. We’re using our trays until they fall apart completely. But if you’ve moved beyond that, shallow natural fiber pots would work, or even the cut-off bottom of a food container with holes punched in the bottom.
You will also need another container not much bigger than the shallow container, to sit beneath it. A 9×5 bread pan works well as the under-container for a 6-cell seed starter tray.
Fill the shallow container with potting soil, and moisten it with water, letting any excess drain out. The seed is so small that it’s not easy to place it exactly, so make shallow furrows or dents in the soil surface, aim a few seed for each depression, and gently cover up the seeds with a bit of soil from the sides. The soil that covers the seed should be soft and light.
Place the shallow container into the under-container, and place the whole thing in a sunny place. Each morning, put a little water in the under-container. For a 6-cell seed tray, this is a tablespoon or two of water. It should be taken up quickly, and the surface of the soil should stay evenly moist. I don’t water at night, since the combination of colder and wetter seems to encourage wilting. The seeds should sprout in about a week.
That’s it! As the seedlings grow, keep putting the bit of water in the under-container each morning. Let them get to 3 or 4 inches high before you try replanting. At that point, they can go into a bigger container or the ground. The plants can then be watered from the top, but for thyme that lives indoors, avoid getting the leaves wet, especially at night.
Oh, and the pine cones shown in the picture? They’re not just pretty – they prevent your cats from digging around in your houseplants!