wallmart plant seed packs and more questions

I have never grown plants B4 , how ever I have been very good at keeping
fish in my 29gal mall mart tank, and I have decided to step up the pace a
bit, give me a bit more to do with my hobby , so I reset up my tank with
some small grain sand slightly lager than what one would find in the sand
box for the roots and topped with lager normal aquarium sand. any way I have
purchased a couple packs of seeds from mall mart and they seem to be growing
very slow. the package says they sprout in 15 days guaranteed lets just say
its taken a bit longer for them to start sprouting its like day 25 and they
started like three days ago , "is this normal ?" -
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- I have also purchased other plants from the local fish/pet store some
grass looking stuff they guy says grows like strawberries and some other
plant as well as a lily plant of some sort "not really keeping track as to
plant types yet " this is more of a first time attempt I figure this first
go is going to fail but then I don't like failure so I am making a serious
effort at this and the plants seem to be doing fine I just want to find as
much advice as possible

I am curious to find out if its really neccary to use chemicals in my tank
the pet guy at the store advised several different types as if its a must.

but then I figure he is telling this to me a person that has been very
successful in my book in keeping fish for several years with out use of
chemicals in my tank. in fact I have been so much more successful than when
I did use chemicals to balance my water "haven't lost a fish since I stopped
using chemicals and quit using tap water " and my water is fine when tested
and I do very little on the water change like next to never mostly let it
evaporate and put spring water back in to replace the evaporated and replace
the filters all the time like every week" kind of expensive " hence the
idea of plants as filters

- note- my ammonia spiked for like a week after I stopped using filters
bought from the store and added plants to my tank but is back to normal


so I wonder if its rely neccary to use chemicals for a planted tank because
I really don't want to if its not required but I also don't want rotting
plants in my tank , any advise for a newbie.