The darkest lavandin is 'Grosso', which has a nice compact flower spike, excellent for drying. It also has a neat habit and a fragrance sweeter than that of many other lavandins. Spanish lavender is a low, sprawling plant, with squat flower spikes and a hint of pine fragrance. Hardy to Zone 8, it is often in full bloom as early as May in our Oregon garden. Silver Frost' is more cold and humidity tolerant than most wooly lavenders.
French lavender has the same blocky flower spike as Spanish, but with a smaller tuft of bracts.
Its leaves are slightly serrated along the margins, as if cut out with pinking shears. Both flowers and foliage are thickly resinous with the scent of lavender and camphor. Though a bit floppy by nature, French lavender is easy to shape. If you live in a humid climate and can't grow lavandin or English lavenders, give French lavender a try. Sadly, it is a temperamental plant that doesn't tolerate excesses of humidity or wetness, but it has produced several hybrids with sturdier constitutions.