How much lemon balm to add to wheat ale?

I plan on brewing an American wheat this week. Here is the recipe (3.5 gal batch):

1065 Yeast

3 lb German pilsner
3 lb German wheat
1 lb Munich

0.3 oz Summit @ 60M (18%)
0.6 oz Willamette @ 15M (4.7%)

OG will be ~1.051, IBU ~33

Just for kicks I am going to flavor this beer with some lemon balm from my garden. Seeing as I have never flavored a beer with herbs, I need some insight as to how to proceed.

How much should I add? I'm hoping for an answer in terms of grams or ounces, but # of leaves would be fine too. I planned on making a vodka extract and adding it at bottling, but should I just add it at flameout or make a tea?

I appreciate your answers in advance and if you want to comment on my recipe, I'd welcome that as well. It seems solid to me, but I am in no way infallible.

Id love to know the answer to this as well. Did you try it out?

I do not know about Lemon Balm. I will say this as I am going to be brewing a wheat next and love a lemon kick to it. I am considering using TrueLemon. I use this for just ice water and it is amazing how true the flavor is. With no additives or presrervatives and pure dehydrated lemon I figure I can't go wrong.

http://www.truelemon.com/true-lemon.html

It's still in primary. I added 1 oz leaves and stems at knockout and tasted some a couple days ago. The lemony flavor was there, but it was a little faint, so I added another 0.5 oz to some rotgut vodka and will add it to taste when bottling. I'll let you know in a few weeks when I have my first taste.