Grits of various types are available in this area from a Farm/Seed stores, like Agway. I use starter grit indoors and turkey grit for any pots I stratify or start outdoors as torrential rains can often wash the seeds right out of the pot. I also mulch all my container plants (large pots) with 1/4" washed pebbles for the same reason plus their heat deflecting properties in our miserably hot summers. Less watering!