Originally Posted by Junkbrew
how in the world do you guys figure out what hops to use and when to use them?...ive been trying to learn as much as i can and thats something i really want to understand better
This is the dilemma. And it's a bigger dilemma the more you learn. You soon realize the more you learn the less you know. The pool of available hops is incredible. You start with this idea like, "C hops work in IPAs". Yes, that is true. But then someone comes along with something off the wall and makes a fantastic beer with seemingly incompatible hops that just shines.
Certain combinations work, and some don't. It's like cooking. Certain spice combinations work well. Look at pumpkin pie. It's spiced with clove, allspice, nutmeg, and cinnamon. They blend beautifully but on their own each is fairly different. Using just allspice wouldn't have the right flavor. You need all of them, but in the right amounts or it sucks.
But if you piggyback on what you know works, you can make some presumptions about additional spices that might work. Grains of paradise might work in pumpkin pie in lieu of allspice since both have a tingly /spicy quality to them. Or adding some black pepper into the mix instead of clove since both are aromatic and spicy. Ginger adds a nice spicy zing that could replace the cinnamon maybe.
Take that metaphor and think of it like that for brewing, which is really like an elaborate form of cooking.
What I would do is look at beers you like. Try to find a recipe and take some notes on what they use for hopping schedules. Look at a lot of recipes. Northern Brewer generously puts recipes for all their beer kits online which lists the hopping schedule. Brewing Classic Styles has a wealth of recipes some of which are a loose clone of commercial beers.
Email breweries you like and ask what they use for hopping schedules. It's our hometown brewery, so I'm biased, but Boulevard is super homebrewer friendly going so far as to tell you an entire recipe, hop amount and time, grain bill, and mash temp if you ask. Avery publishes recipes on their website.
From the original post:
"If I want a nice tropical fruit flavor & aroma how would you use these 3 hops "
The way the question is framed is perfectly. This is how I think you make a great beer. Start with the end in mind. Then find hops that will do this. In most cases, the descriptions available on websites selling hops will describe the flavors somewhat. Reading about the lineage of a hop variety helps establish some common features.
Reading will only take you so far. So be prepared to make some mistakes. You'll learn a lot from the big screwups. I do.