Gadenin日本語Get the appLayering: the method with nothing to go wrong
Thyme roots wherever a stem lies against damp soil, so layering is really just encouraging what the plant already does. Choose a flexible outer shoot, bend it down to the ground, scrape a little bark off the underside where it touches, pin it or weight it with a stone, and cover that section with an inch (2 to 3 cm) of gritty soil. Leave the tip pointing up and sticking out.
Because the layer stays attached to the parent it keeps being fed while it roots, so there is no wilting and no daily attention. It is the best method for a plant with a bare middle: the outer green ring is exactly the material that layers well, and it lets you replace an ageing plant with an identical one at no cost.
- Layer in spring or early autumn Both work. Spring layers are usually ready to detach by autumn, autumn layers by the following spring. Warm soil speeds it up.
- Pin it down firmly Use a bent wire, a tent peg or a stone. A layer that lifts away from the soil in the wind will not root. Contact is the whole trick.
- Keep that patch just damp Water the layered section in dry spells even though you are not watering the parent plant. Roots form in damp soil, not dry.
- Test with a gentle tug at eight weeks Resistance means roots. Once rooted, sever the connection to the parent but leave the new plant in place for another two or three weeks before lifting it.
Mounding gritty potting mix into the bare center of an old sprawling plant layers several stems at once. It is a good way to get four or five replacements from a plant you are about to lose anyway.
Softwood cuttings in late spring
Cuttings give you many plants at once and are the only way to move a variety somewhere else. Take them from soft, non-flowering growth in late spring to early summer, before the stems harden and while the plant is growing strongly. Semi-ripe cuttings, from slightly firmer wood, work in the second half of summer and are more forgiving about wilting.
Expect a good proportion to take and do not agonise over the failures. Stick a dozen for every four plants you want. The commonest reasons for failure are cuttings taken from woody stems, cuttings that wilted before they were stuck, and compost kept sodden.
- Take three inch shoots in the morning Cut three inch (7 to 8 cm) non-flowering shoot tips early in the day when the plant is full of water, and put them straight into a bag out of the sun. A wilted cutting rarely recovers.
- Strip the lower half Pull the leaves off the bottom half of each cutting and trim the base just below a leaf joint. Buried leaves rot and the rot travels up the stem.
- Stick into gritty potting mix Use half compost, half sharp sand or perlite. Push the cuttings in around the edge of a pot, an inch (2 to 3 cm) deep, firm them, and water once. Rooting hormone helps a little but is not necessary.
- Bright shade, not a sealed bag Keep them out of direct sun and lightly covered, but ventilate daily. Thyme rots in a fully sealed propagator far more readily than it dries out.
- Pot on at four to six weeks New growth at the tip means roots below. Pot each rooted cutting into a three and a half inch (9 cm) pot of free-draining compost and grow it on before planting out.
Label cuttings with the variety and the date they were stuck. Thyme cuttings all look identical in a pot, and by autumn nobody remembers which tray was which.
Division, and when not to bother
A sprawling, creeping thyme can be lifted in spring and pulled apart into rooted sections, each with its own roots and green top. Replanted at once in gritty soil these establish quickly. It is a fast way to turn one wide mat into three or four plants.
Upright bush thymes divide badly. They form a single woody crown rather than a spreading mat, and cutting through it leaves large wounds that rot. On a bush thyme, take cuttings or layer instead. Never try to divide a plant whose center is already bare wood: there is nothing living in the middle to divide.
| Method | When | Difficulty | Best for |
|---|---|---|---|
| Layering | Spring or early autumn | Easiest | Replacing an ageing plant with one identical |
| Softwood cuttings | Late spring to early summer | Straightforward | Many plants at once, moving a variety |
| Semi-ripe cuttings | Second half of summer | Straightforward | Using material from the post-flowering cut back |
| Division | Spring | Only on creeping types | Spreading mats with rooted stems |
| Seed | Spring, under cover | Slow | Common thyme in quantity |
Named varieties do not come true from seed. If you want the same leaf color, scent or habit, you have to take a cutting or a layer from the plant itself.
Build replacement into the routine
A thyme plant is productive for roughly four or five years and then declines whatever you do. Rather than discovering that in the spring a plant fails to come back, layer or strike a cutting from each plant in its third year. The replacement is then ready and growing before the parent is lost.
Keep a note of when each plant was propagated and from which parent. Over a few seasons that record tells you which of your plants root readily, which position they survive in, and how long yours actually last in your soil, which is far more useful than any general figure.
Two rooted cuttings a year, taken in passing while you cut the plant back after flowering, is enough to keep a herb bed in thyme indefinitely.