Cedar mulch is the most expensive wood mulch, and with good reason. It decomposes slowly, smells good and may even have some insect repellent qualities due to the oil it releases. Cedar mulch is attractive and heavy enough that only very heavy winds will move it.edar mulch can be spread as a 1- or 2-inch layer over garden soil directly around vegetables. It is more often used, though, as mulch for paths between raised beds.