We thought we would try a little experiment this fall in propagating lavender and starting them in a cold frame. Lavender can be propagated from seed, by layering or cuttings: the latter is the most reliable method. Their are several ways to propagate: hardwood, semi-ripe or softwood cuttings. We are trying semi-ripe cuttings from our Royal Velvet and Grosso varieties. Semi-ripe cuttings can be taken from non-flowering shoots in August. Shoots 2 - 2 3/4 inch long are cut from our healthy plants. Removing the lower leaves and scraping one side of the stem with our fingernail to expose the green.
The stem can then be dipped in rooting hormone and inserted in a mixture of vermiculite and sand. We decided to try a little heavier mix of potting soil, sand and vermiculite because of our colder temperatures and dipping half in rooting hormone and the other half without.
The cuttings should root within eight to ten weeks. We will be removing the tip of the cutting to help produce a branching bush.
Gary build a cold frame from 2 windows we found at a selvage yard and pressure treated wood. The frame is 12 inches on the back side and 8 inches the front to form a slant. The windows inserted in the frame and hinged in the back.
The plants have been in the cold frame for 4 weeks now and we have had to replace the plants that were placed in the back of the frame because it was to hot. We made the mistake by not venting.
We will be watching the weather for frost and make sure we close the lid. We'll let you know about our progress.