You need something to hold moisture, which decomposed granite will not do. You can mix fine decomposed granite into regular potting mix to improve the drainage, but you need to be making a mix similar to "cactus mix" at least.

Keep in mind that plants in containers need to be watered more often than the same plants would if they were planted in the ground.

Would a 50/50 mix of decomposed granite and compost do the trick? I could also add in some peat moss.

Thanks lazygardens.

decomposed granite is excellent for planters. you might want to ask al (tapla) on the container forum. he's got a thing going on there where everyone is going crazy searching for granite.

One might also add some perlite or vermiculite (depends on what you are planting) to the mix of compost and DG to give the mix a little resistance to compressing.

Al tapla