Which flowers are you referring to Cannes? I wouldn't normally suggest giving the actual blooms a feed.

Mg beat me to it!

Watering and feeding are done similataneously i.e. add your liquid feed to the water then water your plants.

There are exceptions when you spray the foliage ( foliage feeding) but until I know which plants you are feeding I can't advise you if this is needed in this instance!