How to Propagate Rosemary from Cuttings and Layering

Take semi-ripe cuttings from this year's growth

The wood you choose matters more than anything else. Look for shoots grown this season that have firmed up but are not yet woody and brown. Bent gently, that wood springs back rather than flopping or snapping. Soft green tips rot before they root; hard old wood sits there for months and does nothing.

The best window runs from late spring through late summer, when the plant is in active growth and temperatures are warm enough to push roots quickly. Cuttings taken in autumn will often root, but they do it so slowly that they spend winter as small unrooted pieces and losses run high.

1. Cut four to six inch shoots Take shoot tips four to six inches (10 to 15 cm) long with sharp clean pruners or a blade. Work in the morning while the stems are full of water, and keep them out of the sun in a bag until you get them into compost.
2. Strip the lower two thirds Pull the needles off the bottom two thirds of the stem. Any leaf below the surface of the compost rots, and that rot travels up into the stem.
3. Trim below a leaf joint Recut the base cleanly just below a joint. That is where the tissue that makes roots is concentrated, and a clean cut keeps the wound from crushing.
4. Choose healthy parent shoots Never take cuttings from a plant with mildew, dieback or gray mold. Whatever the parent has, the cutting takes with it into a warm humid propagator, where it spreads fast.

Rooting hormone is optional for rosemary. It speeds things up a little and evens out the results across a batch, but healthy semi-ripe wood in a gritty mix roots perfectly well without it.

Root them in a gritty, low-nutrient mix

Cuttings need air and moisture at the base, not food. Use a fifty-fifty mix of a peat-free seed-starting mix and perlite or sharp sand, or pure perlite. Rich potting mix holds too much water and contains nutrients the cutting cannot yet use, which encourages the base to rot.

Push the stems in about two inches (5 cm) deep around the edge of a small pot, five or six to a four inch (10 cm) pot. The edge of a pot drains and warms fastest, and clustering them lets you cover the lot with a single bag or lid.

Open the bag or lid for a few minutes every day. Sealed permanently, condensation settles on the needles and gray mold takes the whole batch out in a matter of days.

Tell rooting apart from simply still green

A rosemary cutting can stay green and firm for weeks without making a single root, which is why people pot them up too early and lose them. The reliable signals are new growth at the tip and gentle resistance when you tug the stem. Both together mean roots.

Do not dig cuttings up to look. Every disturbance breaks the fragile first roots, and a cutting checked twice often never recovers. If you must know, tip the whole pot out sideways once and look for white root tips at the edge of the mix, then put it straight back.

1. Wait for the tug test About four weeks in, pull very gently on a stem. If it lifts freely there are no roots. If it resists, roots have taken hold in the mix.
2. Look for new tip growth Fresh pale green needles at the tip mean the cutting is supporting itself and has roots working. Needles simply staying green prove nothing.
3. Pot up individually Once rooted, move each cutting into a three or four inch (8 to 10 cm) pot of gritty potting mix. Handle it by a leaf or the rootball, never by squeezing the stem.
4. Harden off gradually Reduce the humidity over a week or so before moving young plants outside. Straight from a propagator into wind and sun, the needles scorch and the plant stalls.

Layering is the easiest method of all

If your plant has any low branch that can reach the ground, layering will give you a new plant with almost no effort and almost no risk of failure. The branch stays attached to the parent the whole time, so it never has to survive on its own before it has roots. Spreading and trailing forms layer themselves without help.

Choose a flexible branch in spring, bend it down, scrape a little bark from the underside where it touches the soil, and pin it down with a stone or a wire staple with two or three inches of soil over it. Keep the tip pointing upward and clear of the ground.

Check a layer after a full growing season by scraping the soil back. Once there is a solid clump of roots, sever it from the parent, leave it in place for another two or three weeks, then lift and move it.

Why seed is not worth the trouble

Rosemary seed germinates slowly and erratically, often taking three or four weeks with less than a third coming up, and seedlings grow at a crawl for the first year. Worse, seedlings vary: habit, hardiness, needle size and scent all differ from the parent and from each other, so you have no idea what you are raising until it is two years old.

Cuttings and layers are clones. Whatever you liked about the parent plant, its shape, its scent, the fact that it survived your winters, comes with the new plant exactly. For a shrub you expect to keep for a decade, that certainty is worth far more than the small saving on seed.

1. Keep a note of which plants you propagated from Label each new pot with the parent bush and the season you took the cutting. After a few years the plants that came from your toughest, best-flavored parent are obvious, and that record is what lets you keep choosing well.
2. Take more than you need Losses of a third are normal even with good material. Sticking twelve cuttings to get six plants is the right ratio, and spares are easy to give away.
3. Replace old bushes on a cycle Rosemary goes woody and bare at the base with age. Rooting two or three cuttings every few years means you always have a young replacement ready before the old plant fails.