Autumn is the time to take cuttings of lavender. Cuttings around 6 cm long, taken from new seasons growth which has almost, but not quite, "hardened off" are best.
Strip 90% of the leaves off the cuttings to minimize water loss from transpiration. We place the trays of cuttings in our mini "green-houses" but if you want just a few plants then a half filled large pot with a sheet of Gladwrap across the top works well. Using a growth hormone is a good idea and increases the strike rate considerably.
This year we made around 150 cuttings of a number of varieties including French Lavender and English Lavender plus a few different varieties of Spanish/Italian lavender such as "Avondale" and "Kew Red". The trays also contain a few Santolina. These will all eventually be planted out on the dry, sunny banks of the Eastern Terrace. Lavenders are relatively short-lived so every few years we replace old plants with new.