Join Date: Jul 2012
Location: Corpus Christi, Tx
First I have to agree with philip, that is too much light for a low tech 55 gallon. If you don't have algae problems now, chances are you will eventually.
As for ferts, for a low-medium planted non co2 tank Seachem Flourish Comprehensive once a week along with tabs for root feeders should be fine. If you notice deficiencies in your plants later (misshaped leaves, yellowing, spots, etc) then you can target those specifically.
Worth noting, low tech = slower growth. Plus you state the plants are only two weeks old, so they can still be adjusting to your tank. Once they do you should start seeing faster growth.