Thyme, like other woody-stemmed herbs, tends to grow very slowly, and benefits from an early start if grown from seed. Unlike basil and other annual herbs, you shouldn’t count on harvesting thyme in the first (or even the second) year, except for very light picking of leaves.
Zone: hardy to Zone 4
When I Get My Seedling Home
Keep seedlings under very bright light to prevent legginess. Artificial lights are ideal, but a bright (ideally, south-facing) room will work for the short term. You may have to pot on seedlings more than once before they go out to allow for root growth. This is done by transplanting them into a slightly larger container with enough additional soil to keep the container mostly full. Keep the soil moist by daily watering and allow for free drainage so the plants are never sitting water.
Do not transplant outside until night time temperatures are steadily 10°C (50°F) or warmer. This may mean keeping seedlings indoors for up to a month. The plants should not require any fertilizer until transplant time. When seedlings are large enough, harden them off and transplant to the garden or to containers spacing them at 23-38cm (9-15″) apart.
Trim plants back after flowering to encourage bushy growth. Protect container-grown plants from cold as winter approaches, and water only as necessary. Damp, cold soil will kill thyme.
Fresh thyme leaves can be harvested at any time of the year as long as the plants are established. Prune back any dead branches. Whole stems/branches can be clipped and dried whole, or individual leaves can be left to dry in a dark, airy spot for long term storage.
An all around beneficial plant for the garden, thyme is particularly worth planting near Brassicas, as it repels cabbage moths, and strawberries, as it enhances flavour.
More on Companion Planting.