Propagating Herbs From Cuttings — How to Root Them

Taking cuttings is the best way to propagate most perennial herbs — it is faster than growing from seed, produces a plant genetically identical to the parent, and allows you to create multiple plants from a single established herb. Rosemary, thyme, sage, mint, and basil all root readily from cuttings with the right technique. This is also the most economical way to replace an ageing woody herb without buying new plants.

Softwood Cuttings — Spring and Early Summer

Softwood cuttings are taken from the new soft green growth in spring and early summer (May to July). This is the best time for basil, sage, and mint. Take 8–10 cm tip cuttings from healthy non-flowering shoots. Cut cleanly just below a leaf node with sharp scissors or a blade. Remove the lower leaves, leaving only two or three pairs at the top. Dip the cut end in rooting hormone powder or gel, then insert into a pot of moist cutting compost (50% multipurpose compost, 50% perlite). Keep in a warm, bright spot out of direct sun and maintain humidity by covering with a plastic bag or propagator lid.

Semi-Ripe Cuttings — Late Summer

Semi-ripe cuttings are taken in late summer (August to September) when the base of the current season's growth has begun to harden. This timing is particularly good for rosemary, thyme, and oregano. Take cuttings 8–12 cm long and strip the leaves from the bottom half. A slight firmness at the base of the cutting indicates the wood is semi-ripe — the ideal state. These cuttings root more slowly than softwood but are more robust and less prone to rotting. They can be left in a cold frame or cool greenhouse over winter and potted on in spring.

Rooting Mint and Basil in Water

Mint and basil can be rooted simply by placing cuttings in a glass of water on a bright windowsill. Take 8–10 cm cuttings, remove all but the top leaves, and stand in 3–4 cm of water. Change the water every two to three days to prevent bacterial build-up. White roots usually appear within one to two weeks for mint, slightly longer for basil. Once roots are 2–3 cm long, pot into compost — transplant before roots become too long and matted. Water-rooted cuttings need to be kept consistently moist after potting until they adapt to compost.

Getting the Conditions Right

Consistent warmth (18–22°C) and humidity are the two most important factors for rooting herb cuttings. Without warmth, rooting is slow or does not happen; without humidity, cuttings wilt before roots can form. Never put cuttings in direct sun while rooting — bright indirect light is correct. Keep the compost barely moist; overwatering causes cuttings to rot before roots form. Rooting hormone is not strictly essential for mint, basil, or sage but significantly improves success rates for rosemary and thyme, which root more slowly.

Checking for and Potting On Rooted Cuttings

Resist pulling cuttings out to check for roots — wait four to six weeks and watch for signs of new top growth, which indicates roots are forming. Alternatively, very gently tug the cutting: resistance means roots are developing. Once a cutting has clearly rooted (new leaves appearing, roots visible through drainage holes), pot on into a 9–10 cm pot of standard potting compost. Grow on for a few weeks before moving outdoors or placing in its final position.