Munstealasted 5 years for me in clay soil but was in a spot that was midway down a gradually sloping area.
I'm trying Hidcote now hoping to get one that will survive our winters for the bees.
I think lavender needs moist but we'll drain ng soil but I'm no expert. Just hoping to get seeds from my plants to sow each year in hopes of getting plants that are adjusted to my garden conditions.
I use a lot of lavender medicinally as its a powerful herb.