Updated: Aug 29, 2022
I get a lot of questions about the top dressing I use in my pots. I use rice hulls which is a byproduct of making rice. They are anti fungal in nature and they help maintain moisture levels in wet seasons. They also prevent germination of seeds so they are great for weed suppression. Several folks have asked if you can use them as mulch in landscaping. My hunch is that they would blow away or float away as they are very light.
Here is a link if you want to know more about rice hulls. http://www.riceland.com/uploads/pages/rice_4pages_1-2012.pdf
If you like to dabble in propagation and want to try some yourself, you can usually find them at your local home brewers supply store.