I used Lavender from my plants in the backyard, last summer. I might a great Lavender wit. I used a little less than .15 oz of the flowers, and probably .1 oz of leaves. I soaked them in grain alcohol for 1 week and added them to the secondary. I also used lemon zest, and the lemon stood out more than the lavender. I wouldn't boil the lavender, (boiling brings some crazy stuff out of herbs), but I might steep .25 oz after the boil and and .25 oz to the secondary. If you're doing an IPA I wouldn't go crazy on the hops, they will easily overpower the lavender.