Lavandula x intermedia or Provence Lavender is a cross between English Lavender (Lavender angustifolia) and Portugese Lavender (Lavandula latifolia) the latter providing the heat tolerance for this plant to thrive in warmer climates.
It has large flower heads, can handle humidity, it produces the strongest fragrance and is also good for low hedging - as can been seen in all the tourism photos of Provence in France where visitors flock in July (mid summer) to see the never-ending rows of spiky blue buns that fill the air in the entire region with the musky warmth of Lavender oils.
It is an important crop in the Luberon which produces much of the oils for the French perfume industry.
These are drought tolerant plants that love plenty of sun and are as hardy as old boots, while attracting bees and butterflies in profusion.
Naturally they make excellent cut flowers which last well.