How do you measure Alpha Acidity in the hops you grow? Do you just go with the average AA for a specific variety?
That’s one way to do it, just estimate, but you never know where you’ll be.
Another thing to do is small test boils with hops of known AA.
But the only real way to know is to send a sample off for lab testing, that will give you a good answer for your crop. It’s not worth it to me, but YMMV.
I always make a pale ale to start out, taking a guess as to the alpha acid that is typical or average of the hop variety. Then if it turns out too bitter, call it an IPA. If not bitter enough, call it a blonde ale. From there, when you make the second and third batch, you will be able to come amazingly close to figuring out the true alpha acid based on taste alone.
I also sometimes like to mix my homegrown hops (at least the bittering addition) 50/50 with a known similar alpha acid variety. Then I don’t need to “waste” as much of my homegrown hops figuring out the alpha acid.
Homebrewing software such as ProMash, StrangeBrew, BeerSmith, etc. is key to figuring out your alpha acid based on taste. First assume something, then iteratively adjust it based on taste for successive batches. You’ll come really really close on the third or fourth batch, and very reasonably close even on the second batch.
I agree with this approach. You can make some excellent beers once the hops are dialed in.
There is some pride that you can take when one of your homegrown hops beers wins awards, and impresses your friends.