How long before you can't reuse a yeast cake?

Hi all,

I have two batches of beer going right now (Scottish Ale and Blonde Ale) and I want to try reusing a cake for my next batch of cider. They've been in the fermenters almost a month and I'm going to bottle soon. Are the yeast cakes still good? How long can you go before it's no good?

Incedentally, I'm trying to make a sweeter cider so I was thinking I'd throw it down on the Blonde ale cake. Maybe do a darker cider on the Scottish Cake.

Take care,

Jim

The clock starts ticking when you rack off the cake. Any time within two weeks should be good, if you keep the cake cool.