Isn't that a 2 part grow nutrient? Part A and Part B? Part B is 1-5-8. You really should be using both as some nutrients are in part A and some in Part B. They are meant to be used together. If you look at Part A 5-0-2 there is no phosphorus and without looking at the label I can't say what else is missing. P is an important macro element that is not just used by the plant during flower but also plays an important role in plant development during the vegetative stage.
If you don't have part B then you should get it. Having said that you do need to reduce the nutrient strength of your feed. I don't know what kind of soil you're growing in or what's in it but those plants are not that big for 5 gallon containers and you likely didn't even need to start feeding yet. Their feed chart might say to start feeding at week 1 but many of those charts are based on soil less growing. If you start feeding at week 1 when growing in a rich soil you end up overfeeding.