[yso191]

I am on a kick experimenting with dry yeast.  Part of my experiment is to just dump the pack into the wort rather than pre-hydrating it.  I know I will lose some yeast cells doing it this way, but If I'm going to prep yeast I'll do a yeast starter.  To me the advantage of dry yeast is that it is quick (well, and cheaper).

My question is: at what gravity level does under pitching become a concern?  My next brew is an AIPA with an OG of 1.058.  Will one pack do, or should I add a portion of a second?  In case it matters the yeast in question is US-05.

[HoosierBrew]

I've always pitched a second pack at 1.070+ and only recently started rehydrating. I've never had any ill effects,ie., always had good attenuation and yeast character.    Disclaimer - I prefer liquid cultures but I've used a ton of S05 for short notice brewing.

EDIT -  I think Denny said he'll go to 1.075 on one packet.

[Wort-H.O.G.]

i just did an IPA 1.061 and rehydrated 1 pack of us-05. results: splendid IMO. everything as expected and tastes fantastic.

[brewinhard]

I am along the lines with Hoosier.  If my wort is over 1.075 I will consider adding a bit more from a second pack, but I always have rehydrated with great results.  Under 1.075, 1 pack will suffice with no issues (providing proper aeration). 

[jimmykx250]

I do a house beer at 1.060 and one pack of us-05 does just fine. I have pitched dry quite a few time with no issues. Let us know how it works out for you.

[a10t2]

I wouldn't worry too much about under-pitching ales until the pitching rate gets below about 0.5 million/mL-°P (assuming you're targeting 0.75). If a pack of dry yeast contains ~200 billion viable cells, that would be around 1.080 OG for rehydrated yeast, or 1.040 for un-rehydrated. Ultimately, though, let your tastes decide.

[erockrph]

For ales - up to 1.075 gets 1 pack of unrehydrated S-04 or US-05. For lagers I'd pitch two packets of 34/70 for anything up to a smallish doppelbock. If I only have 1 pack and I'm at the borderline of gravity for 1-pack, then I'd consider rehydrating as an insurance policy.

[pete b]

I am on a kick experimenting with dry yeast.  Part of my experiment is to just dump the pack into the wort rather than pre-hydrating it.  I know I will lose some yeast cells doing it this way, but If I'm going to prep yeast I'll do a yeast starter.  To me the advantage of dry yeast is that it is quick (well, and cheaper).

My question is: at what gravity level does under pitching become a concern?  My next brew is an AIPA with an OG of 1.058.  Will one pack do, or should I add a portion of a second?  In case it matters the yeast in question is US-05.

To me rehydrating is so close to doing nothing that I do it just in case it helps.

[Wort-H.O.G.]

http://brulosophy.com/2014/09/15/sprinkled-vs-rehydrated-dry-yeast-exbeeriment-results/

interesting experiment on dry vs. re-hydrating yeast.

[woodlandbrew]

Here is another experiment you may be interested in: http://www.woodlandbrew.com/2013/02/rehydrating-safbrew-yeast.html