• Dry-hopping is a great way to get a bright hop aroma in your beer along with a bit of flavor without adding additional bitterness (though a highly dry-hopped beer may have some perceived bitterness). You can dry-hop any beer, but generally it is reserved for more hop-forward styles (Pale Ale, IPA, Pilsner, some Stouts, California Common, etc.).
• Dry-hop after fermentation is complete to avoid stripping out hop volatiles by carbon dioxide that is gassing off. Some brewers choose to dry-hop directly in the primary after fermentation is complete or you can transfer to a secondary to do your dry-hopping. It all depends on how confident you are in the health of your yeast and how long you plan to dry-hop for post-fermentation.
• If using hop pellets, there is no need to put the hops in a hop bag. Simply put them in the top of the fermentor, and they will settle to the bottom (sometimes crash cooling will expedite this process). If using whole hops, a muslin or nylon hop bag is recommended. The bag of whole hops will naturally float, so you can use glass marbles or stainless steel ball bearings to help weigh the bag down (be sure to sanitize them first!).
• Hops have some natural anti-microbial qualities, and properly fermented beer should hinder the growth of any unsavory organisms. Therefore, there’s no need to worry about adding new hops to the beer post-fermentation.
• Most brewers to choose to dry-hop for 3-7 days. There is some anecdotal evidence that prolonged dry-hopping will lend a grassy, vegetal character to the beer. I’ve had success with even dry-hopping in the keg when I know a beer is going to be consumed quickly. I use a metal tea ball stuffed with hops to prevent the dip tube from clogging.
• NERD ALERT! Hop oils are made up of hydrocarbons and oxygenated compounds. The former includes such compounds as humulene (herbal/spicy), myrcene (citrus/pine), & caryophyllene (herbal/spicy as well), which are very volatile, and most are driven off during the boil as well as fermentation. Oxygenated compounds like geraniol and linalool (both floral-like characteristics) are less volatile. Dry-hopping allows you to “replenish” those oils that were driven off.