How to tell what's going on
Part the stems and look at the center. Gray, bare, brittle stems with leaves only at the outer tips mean the plant is aging, which is normal for thyme after two or three years. Scratch a stem with a fingernail: green underneath means it's alive, brown and dry means that stem is dead. Then check the crown and the soil. If the base of the plant is soft and brown, the soil stays wet after rain, and stems wilt without recovering, root rot is the more likely cause. Iowa State University Extension notes that thyme is susceptible to root diseases in saturated soil.
Why it happens
Age is the most common cause. Thyme is a small woody shrub, and Iowa State notes that older plants can become woody, sparse, or open in the center. New growth comes mostly from the stem tips, so each year the green moves outward while the inside turns to bare wood, and skipping regular trims speeds this up. Wet soil is the second cause. University of Illinois Extension notes that poorly drained soil, especially over winter, shortens thyme's useful life. Rich soil and frequent watering also produce weak, sprawling growth, and Iowa State advises fertilizing thyme sparingly, if at all.
What to do now
If the plant is mostly woody but the outer stems are still green, renew it. University of Illinois Extension suggests cutting thyme back severely in spring to push out new, tender stems; cut each stem back to a point right above where green leaves or buds are showing. After it flowers, shear it lightly to keep it compact. If the center is dead, dig the plant in spring, cut away the woody middle, and replant the healthy outer sections as divisions. You can also root 3- to 4-inch cuttings taken from soft green tips; Iowa State notes that stem cuttings root readily.
Next time
Plan on replacing thyme every few years. University of Maryland Extension recommends renewing plants every few years, and Iowa State says the same, so keeping a few rooted cuttings or divisions on hand makes the swap painless. Plant in gritty, well-drained soil, a raised bed, or a pot of fast-draining mix, and once plants are established, water only during long dry spells. Trim stem tips through the season as you harvest. Where soil is heavy clay or winters are wet, a container or raised bed often keeps thyme going longer than an in-ground spot.
Growing it again? When to plant thyme for your ZIP code
- When and how should I harvest herbs for the best flavor?Harvest herbs before they flower — leaf essential oil concentration peaks right before flowering, and leaf production tends to decline once the plant shifts energy to seed production.
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- My soil is heavy clay — can I actually grow vegetables in it?Yes, but clay soil needs amendment over time — raised beds with imported soil offer a faster path, while in-ground clay improvement with organic matter takes several seasons to become reliable.