GigaFemto said:This is a consequence of the yeast aging rate. You need to put in the packaging date of your yeast, then BeerSmith calculates the yeast viability based on the brew date relative to the packaging date. If you push the brew date out by two months without changing the yeast packaging date the yeast will be less viable and you will need more packs or need to build more of a starter.
--GF