Hi, Diane! Your inquiry is a good one. It caused me to take a hard look at the website's usage information. It could stand improvement and is now on my to-do list. In the meantime, here's a quick guide to the use of Osmocote Plus Outdoor & Indoor in containers -- 6" pot = 1 quart of soil = 1/4 ounce of Osmocote 10" pot = 3 gallons of soil = 2 1/2 ounces of Osmocote 12" pot = 5 gallons of soil = 4 ounces of Osmocote 16" pot = 10 gallons of soil = 8 ounces of Osmocote 18" pot = 15 gallons of soil = 12 ounces of Osmocote 24" pot = 25 gallons of soil = 21 ounces of Osmocote 30" pot = 30 gallons of soil = 25 ounces of Osmocote If you don't get the measurement exactly right, not to worry. Osmocote is very forgiving. It can be over applied by a factor of 3 but will not harm the plant. Bob Stohler, website manager, for Marianne Binetti