Oh, one more thing, assuming you're using dry yeast. If I knew I had to let a beer sit in primary for 4-5 weeks, I would rehydrate dry yeast before pitching instead of pitching it directly into the wort. Here's why...
When dry yeast are reintroduced into a solution, as they rehydrate themselves, they don't have control over what passes through their cell membrane. When you pitch dry yeast directly into wort, sugars that they normally break down prior to consuming get passed through their cell membrane. This can cause the yeast cell to "burst" and die. If they rehydrate in water, they don't have this problem and yeast viability is greater. So pitching dry yeast onto wort can reduce overall yeast viability and result in more dead yeast cells sitting in the wort, which in theory, could cause "off-flavors" depending on beer style, time, etc. In most flavorful ales and because most primary times are 1-3 weeks, this isn't a big concern. But if I had a beer in primary for upwards of 5 weeks, I wouldn't want those extra dead yeast cells sitting in there the whole time.
Whichever yeast you're using, check out their website for rehydrating instructions. If they don't have any or say to pitch it directly onto wort, don't listen to them. They're just dumbing it down for homebrewers. Check back with us for how to rehydrate.