Preheat oven to 350°F (175°C) and grease a 9×5-inch loaf pan.

In a bowl, whisk together flour, culinary lavender, lemon zest, baking powder, baking soda, and salt.

In a separate bowl, cream softened butter and granulated sugar until light and fluffy.

Add eggs one at a time, mixing well after each addition.

Blend in vanilla extract.

Alternately add dry flour mixture and buttermilk to the creamed butter mixture, beginning and ending with dry ingredients. Mix until just combined.

Pour batter into prepared loaf pan and smooth the top with a spatula.

Bake until a toothpick inserted into the center comes out clean, about 50–60 minutes.

Remove from oven and let bread cool in pan for 10 minutes, then transfer to a wire rack to cool completely.

For the glaze, whisk powdered sugar, lemon juice, and lemon zest until smooth and pourable.

Drizzle glaze over cooled loaf and let set before slicing.