Watch the lavender plant as it prepares to bloom. Wait until the bottom third of the blossom begins to open before you clip the flowers. The top two-thirds of the blossom should still be closed when you harvest the flowers.
Clip the lavender flowers from the plant in the morning after any overnight dew dries from the plant. Use pruning shears to clip the stem beneath the flower. Cut the stem just above the point where it changes from dark green to light green. If you cut below this point, you may cut the stem so low that it will not be able to resume growth.
Leave the flowers on the stems if you wish to dry them. Bundle 10 to 15 stems together with a rubber band, and hang them upside-down in a dark and dry location. Leave the lavender blossoms hanging for approximately two to three weeks to dry them completely.