I apologize if my questions are elementary, but I’m trying to get that learning curve to flatten out.
On Friday morning I’m going to brew the Belgian Strong Dark Ale from Zymurgy May/June 2010. The recipe calls for a trappist ale yeast. Do different strains of yeast require different lengths of time for fermentation and if so, how do I get that information? Also, if fermentation takes longer than a week or two, does that need to be accomplished in secondary?
All Belgian yeasts act differently. Even the identical strain will act differently. Don’t approach them with a one-size-fits-all attitude. Let each yeast do what it wants to do. Let it work until it’s done. Let the temperature rise without trying to constrain it. Leave it in the primary until it’s done, rousing if necessary.
Give it a good environment (nutrients, oxygen, temperature) and you’ll reduce the variability, but there still will be some idiosyncrasies with each. If you try to bend it to your will, it will punish you.
Great advice as always from Gordon. And, if you use wyeast 3787 make sure you have a blow off tube.
In addition to Gordon’s advice, estimate and target your gravity based on the typical attenuation prescribed by the manufacturer. I find the manufacturer’s prescribed attenuation levels to be fairly accurate but that also depends on your grist and your mash temps as well so you will also want to take that into account.
As Gordon stated, the strains will vary as well as the batches. There’s also limits on alcohol tolerance so keep an eye on that.
Good Luck.
How does one know if their yeast needs to be “roused”?
Once your fermentation appears “done” (that is, the gravity hasn’t changed for a couple of days), see if your final gravity is within the attenuation range specified for your particular yeast. If it’s not down into that range, then your fermentation may have stalled and you’ll need to “rouse” the yeast to try and get things going again.
So then to accomplish the rousing do you need to add oxygen, sugar, more yeast?
No, it’s more a matter of stirring the yeast up from the bottom by grabbing the fermenter and giving it a good swirl.
That makes good sense.
Thanks for all the input, guys. I don’t know what took me so long to begin taking advantage of this forum. This is just awesome.
That is so appropriately put! 
How much does the rousing really help? I’m thinking that this rousing would mostly be needed with heavily flocculating yeast. Those yeasts should quickly sediment again after rousing.
Kai
My experience is that rousing is seldom necessary. When I’ve needed to do it, the results seemed to vary between minimal and none.
IMHO Gordon nailed this response, I’ll add that all yeasts act differently, not just Belgian yeast.