Gadenin日本語Get the appTake cuttings before you need them
Lavender is a short-lived shrub. Even a well-grown plant starts opening at the base somewhere between its eighth and fifteenth year, and there is no pruning cure for that. The way to keep lavender in a garden permanently is to root a few cuttings every three or four years, so that replacements are already a decent size when the old plants need removing.
Cuttings also let you keep a plant you like exactly as it is. Seedlings from your own plants vary in flower color, habit and scent, and the offspring of hybrid lavandins are usually poor. If the plant is worth keeping, take cuttings rather than saving seed.
Semi-ripe cuttings in summer are the reliable method
The best material is a semi-ripe shoot taken in mid to late summer: firm at the base, still soft at the tip, and with no flower bud. Shoots that are carrying or have carried flowers root poorly, because their energy has gone into flowering. Look low down and inside the plant for the short leafy side-shoots that never flowered.
Softwood cuttings taken in late spring root faster but wilt easily and need more careful humidity. Hardwood cuttings taken in autumn work too but take until the following spring. For most gardeners, semi-ripe cuttings in summer give the highest success rate for the least fuss, typically rooting in four to six weeks.
- Cut in the morning Take material early, before the plant has lost water to the sun, and put the shoots straight into a bag out of direct light. A wilted cutting rarely recovers enough to root well.
- Choose non-flowering shoots Pick side-shoots three to four inches (8 to 10 cm) long with no flower stalk and no flower bud forming. Strip the leaves from the lower half so no leaf will sit under the compost.
- Trim below a node Cut cleanly just below a leaf joint with a sharp blade. A torn or crushed base rots instead of rooting. Rooting hormone is optional with lavender and makes only a small difference.
- Use a gritty, low-nutrient mix Half seed-starting mix and half sharp sand or perlite. Rich compost holds too much water and rots the base of the cutting before roots form.
- Insert and firm Push the cuttings in so the lowest leaves sit just above the surface, five or six around the edge of a five inch (13 cm) pot. Firm gently and water once from below to settle them.
- Bright shade, not a sealed bag Stand the pot in bright light out of direct midday sun. Lavender leaves rot in a sealed humid bag; a propagator lid with the vent open, or nothing at all in a sheltered spot, works better.
Do not water again until the mix is genuinely drying. Overwatering is the main reason lavender cuttings fail, and it looks like a fungal problem when the stems blacken at soil level.
Know when they have rooted, and pot on promptly
The first sign of rooting is new growth at the tip and a cutting that resists a very gentle tug. That usually comes four to six weeks after insertion in warm weather. Do not keep pulling at them to check; one careful test at four weeks is enough.
Once rooted, pot each cutting individually into a three and a half inch (9 cm) pot of gritty potting mix and grow them on in a bright, frost-free place. Pinch the growing tip once when the plant is about four inches (10 cm) tall to make it branch, which is what produces a dense plant rather than a single leggy stem. Plant out the following spring after the last frost.
| Method | When to take | Time to root | Success rate |
|---|---|---|---|
| Softwood cuttings | Late spring, from soft new growth | Two to four weeks | Good, but wilts easily |
| Semi-ripe cuttings | Mid to late summer, firm at the base | Four to six weeks | Best for most gardeners |
| Hardwood cuttings | Autumn, from ripened shoots | Over winter into spring | Slow but low effort |
| Mound layering | Spring, on an old open plant | One full season | Reliable on plants with bare centers |
| Seed | Spring, needs chilling first | Two to six weeks to germinate | Variable offspring, poor from hybrids |
Mound layering rescues an old open plant
If a plant has already split open at the center and you have nothing to take cuttings from except tip growth, mound layering gives you rooted plants without disturbing anything. In spring, heap a free-draining gritty soil mix into the open middle of the plant, burying the lower part of the splayed woody stems and leaving the leafy tips clear.
Keep the mound just moist through the season. By the following spring many of the buried stems will have rooted where they were covered. Cut each rooted stem away from the parent, lift it with its roots, and grow it on in a pot for a season before planting out.
Seed is a last resort
Lavender seed germinates unevenly and slowly, needs a period of cold before it will move reliably, and produces plants that vary from the parent. Hybrid lavandins are largely sterile, so seed from those is not worth sowing at all. Growing lavender from seed makes sense only when you want a large number of plants for a hedge and do not mind variation.
If you do sow, chill the seed for three to four weeks in damp vermiculite in a refrigerator, then sow on the surface of a gritty mix at around 65F (18C) with only the lightest covering. Expect germination to spread over several weeks and expect roughly half the seedlings to be worth keeping.
Whichever method you use, label everything with the date taken and which parent plant it came from. A tray of unlabelled lavender cuttings is indistinguishable in eight weeks, and knowing which parent rooted best tells you where to take material from next time.