Went to the clemantis link long enough to bookmark it. So when you say bloom booster are you talking about the first number being the highest? Like 20-10-10? I think the first is nitrogen. Pathetic knowledge over here.
No, the middle number. I love a granular new lawn starter formula that is 10-18-10 for all of my young (3 years and less) fruit trees.
You can give something a BIG kick in the pants with a Miracle Grow-like powder (mixed with water) that can be found in a 10-52-17. Jung’s sells a nice array of formulas.
I used that 10-52-17 mix on my strawberries this season when I first noticed buds, and I’ve been picking a QUART every few days and the patch is only 8’x4’! And, of course, PUPPIES have been picking some, too!
The Jung-brand fertilizers (’Jump Start’) are in boring B&W plastic packaging, but there are some awesome formulas - and a little goes a long way, so a packet will last you through a few seasons if you store it properly.
https://www.jungseed.com/C/213/FertilizersGrowthBoosters