Thyme Going Woody — How to Rejuvenate It

Thyme naturally becomes woody with age — it is a sub-shrub, not a soft herbaceous plant, and woody stems are part of its natural lifecycle. The problem comes when there is so much old wood that the plant produces very little of the soft, harvestable new growth you actually want to cook with. A combination of timely pruning and knowing when to start fresh is the key to keeping thyme productive.

How Quickly Does Thyme Go Woody?

Most thyme plants become noticeably woody within two to three years without regular pruning. In the first year you get lush, soft growth; in the second year the lower stems begin to harden; by year three the centre of the plant can be entirely bare brown wood with green growth only at the branch tips. Without intervention, yield drops significantly and the plant eventually dies back from the centre outward.

Annual Pruning Prevents Excessive Woodiness

The single most effective thing you can do is prune thyme hard every year in spring, just as new growth begins. Cut all stems back by about two-thirds, but — critically — always leave several sets of green leaves on each stem. Like rosemary, thyme will not regenerate from bare, leafless wood. Trim to just above a node where you can see leaves or green buds. This annual reset keeps the plant bushy and delays the need for replacement by several years.

After Flowering — A Second Trim

Thyme flowers in early summer and should be cut back lightly after blooming. This light post-flowering trim removes spent flower heads and encourages a flush of fresh leaf growth for late summer and autumn harvests. Do not cut as hard as the spring prune — just remove the top third of flowering stems. This second trim also prevents the plant channelling energy into seed production.

Can You Cut Back Into Old Wood?

If thyme has already become very woody, you face a dilemma: you cannot cut back into bare wood, but there may be very little green growth left to cut back to. In this case, check each branch carefully. Some may have green buds tucked near old nodes — cut to just above these. Branches that are entirely bare and brown are dead wood and should be removed entirely. If fewer than half the branches have any green growth, it is usually better to start with a new plant.

When to Replace Thyme Entirely

Even with good care, thyme plants typically need replacing every four to five years. When the centre of the plant is dead, the remaining stems are thin and weak, and pruning no longer stimulates bushy regrowth, it is time to start fresh. Take cuttings from the healthiest tip growth in early summer before discarding the old plant — 8–10 cm tip cuttings root readily in a free-draining compost and will give you new plants that last another four to five years.