Propagating Grosso Lavender

I have tried unsuccessfully to take cuttings from a lavender plant named Grosso. I start the tip cuttings in a seed starting mixture and cover with plastic wrap. I seem to have a struggle keeping them from rotting or drying. Do you have any tips that might yield me a plant?

We have same experience. Grosso seems to be more difficult to root from soft cuttings than other lavenders. Try taking semi-hardwood cuttings, especially in the early spring, from dormant plants, before the branches leaf out. Use Number 2 Stimroot rooting hormone powder.