The Right Time
The right time to add the hops to the fermenter is just as the fermentation starts to slow down. This is usually apparent by the head (or kraeusen) starting to diminish, which usually coincides with a decreased bubbling in the airlock. Typically this will be three to four days after fermentation has begun. If you use a single-stage fermenter, just add the hops. If you use a secondary fermenter, rack the beer now and add the dry hops to the secondary.
The wrong time to add the hops is at the very beginning of fermentation, or close to it. Hops are not a sterile product and putting them in too early can cause a contamination in your beer.
If you wait for the right time, several factors are at work in your favor. The beerâs pH will have fallen to the point where the organisms on the hops canât survive, and the alcohol now present also serves to kill them. You also have a healthy yeast population in your beer, and this yeast will tend to starve out the other organisms. There is no risk of contamination from dry hopping if you do it at the right time.
The final good reason for waiting is that during the initial stages of fermentation large quantities of CO2 are being generated, and this will scrub the hop aroma right out of your beer.
