How often should mulch be replaced?

[ZandraJoi]

We don't use mulch anymore but we used cedar chips awhile back. While it was more expensive, it was natural with no chemicals. What I'd do is top it off every year. After a few years, I'd remove the layers & put fresh down. See how well the mulch is doing. If you see more weeds coming through, mold, fungus growing in it, that's time to replace it.
If you want cheap mulch, get a hold of Tree Services. Some of them sell or even give away the mulch.