I brewed with heather in a gruit, and spent some time beforehand experimenting with teas in combinations of other herbs. There is a lack of solid information regarding gruits, much less heather. My reading material included GruitAle.com, Radical Brewing, Sacred Herbal and Healing Beers, forum searches on HBT and AHA, etc.
For bittering, the recipes I found call for a pound or more per 5 gallon batch. Heather flowers are tiny and very light, so 8oz will take up an entire 8x9 nylon boiling bag. If you add it directly to the boil, you will need to strain it out before adding to the fermenter. I imagine they'll clog an autosiphon just as easily as whole hops. In my case, I supplemented with other, stronger bittering herbs.
For flavor, many recipes tell you to pour the hot wort directly through the heather. This is highly inefficient, and you won't get the heather's full flavor potential. This might work with fresh heather, but the only way I know how to obtain that is to grow your own, and harvesting heather is time consuming.
I found that the best way to get heather flavor and aroma is to make a tea. Either use hot water or wort. Fill a french press, 2-4oz at a time, and steep for 5-15 minutes. Pour this right into the fermenter or cooling wort. You can do this as many times as necessary.
Here is the 5gal gruit recipe that I made:
- 10 lbs Pale Malt, Maris Otter (3.0 SRM)
- 1 lbs Cara-Pils/Dextrine (2.0 SRM)
- 8.0 oz Caramel/Crystal Malt - 20L (20.0 SRM)
- 8.0 oz Caramel/Crystal Malt - 60L (60.0 SRM)
- 2.00 oz Mugwort, Dried (Boil 60.0 min)
- 2.00 oz Yarrow, Dried (Boil 60.0 min)
- 4.00 oz Heather Tips, Dried (Boil 60.0 min)
- 4.00 oz Heather Tips, Dried (Tea w/ 4c hot wort)
- 2 Pkgs Nottingham Yeast
Measured OG: 1.072
3-4 week fermentation at 65F
Est ABV 7.1%
The mugwort, yarrow, and half the heather went in a nylon boiling bag. The herbs also soaked up more water than anticipated, and I ended up having to top off my fermenter with 1/2 gal more water. I had originally intended to scale back the yarrow, but I figured the high gravity needed the stronger bittering that it would bring. I suggest you research this ingredient before using. "You're on your own". I will edit this answer in a couple months with tasting notes, but the wort tastes excellent. The next gruit will have elderberry in addition to the heather.