get a blooming fert and use that up untill the last two weeks of flowering.when u think there is only two weeks left start to flush ur plants. this means watering them with pure h20 and not giving them ne ferts wot so ever. this will get rid of any excess chemicals and make the buds taste like they should, rather than harsh and nasty.to flush ur plants (if ur growin soil, cuz i dont have a clue bout hydro) each time u water keep pouring water on them till the colour of the water comming out the bottom of the pots is clear. once u have achieved this dont fertilize again and only water after the soil has dried about 3cm down from the top