Surely there is more than one way to skin a cat. I would not want that high of an N. for trying to bloom. I would try something around 2.5-3 percent on there if they belonged to me. Course I do the same thing with the grass I have to mow each weekend or so. 3% is just about right for a lawn should be similar for other kinds of grass too. Now I dont try to bloom St. Augustine but if it gets a high dose of N if just grows crazy fast and you wind up with a lot of veg growth aka a thatch problem. I would go to the feed store and buy some rabbit food pellets. They are less than 10 bucks for 50 lbs last I check and so happens about 3 on the N scale. Pelletized from Alfalfa. Throw a handful around the base of the plants about once a week. That should work. Try this and kindly report back with the results. Thanks.