That stuff is just fine. Just remember that MJ is not anything like a tomato plant. I think most people think that since it looks somewhat similar it must take the same food, that is the wrong way to look at it. Think of feeding this way; vegetative stage or growth stage your plant needs more nitrogen and during the flowering stage your plant needs more phosphorus. Like That Crazy Vancouver Guy said give it at least half the strength. I would personally give it less than that and then work my way up. You don't want to burn your plants with too much.
I have found that the stuff from FoxFarm works well and it is usually in a concentrated liquid that gives that plant things that help it absorb the nutrients better. These types also create a better root structure which results in a healthier plant altogether. Hope this helps you. Peace.