There are lots of ready made nutrients on the market some aimed at cannabis some not. In the end there’s not much difference between any of them. As long as the nutrients are complete and given in the correct dosage results should be good.
Cannabis is a nitrogen lover and whilst in its growing stage it will need a feed with extra nitrogen. When flowering starts it will require extra phosphorus and potassium instead. This is why a lot of cannabis nutrients come in two or even three part formulas.
If a plant looks under fed check the p.h. of the medium and water before adding more nutrients. If your growing in soil make sure your not over watering and suffocating the plants roots. Soil should be allowed to dry a little between watering.