Big Bloom is used both in veg and in flowering. Tiger Bloom is only used in flowering. If you can only get 1 get Big Bloom because you'll get more use out of it. I find that it makes my plants very healthy when used alone in veg. In flowering though, it's on- I use all FoxFarm nutes (Grow Big, Tiger Bloom, Big Bloom, Open Sesame, Beastie Bloomz, and Cha-Ching). I like FoxFarm- it's easy and I get great results.