Our temple traditions and major Agamas actually do not permit any sort of decorations of idols of main pratishta or ulsava beras with artificial or syntethic nature beyond what is consecrated at the time of initial installation..
and change of shape of the idol or the precints of the house of God are not permitted..
except as directed by agamas or tantras and to be effected through the strict procedures..
starting with deva prashnam etc..
Even decorations with natural materials like flower or leaves or twigs are expected to remain only for just a day at the most..
even the most precious thing placed with the deity becomes obsolete within hours.. not to be reused..
I think only tulasai... a very innocuous leaf is permitted to be reused..
Of course we do so many things..
we decorate the idol with external fittings which changes the appearance, sex, gender, and the bhaava of the pratishta.. and we even advertise about it, publish snaps about it..
Where is the permission for all this?
If you are talking about traditions we have to think of all such aspects..
Next question continuing namasankeerthanam without sandyavandanam.. using non agamic, non vedic non tatric means and hymns for worship of traditionally consecrated moothis and vigrahas.. are we doing right things?
Using garlands of lemon, Vada, vettrila etc for decorating the moorthy either utsava or moolm...
where is it permitted..?
The Gurukkal or Azhvar may permit it because he has no chioice..
Or he is
ignorant...--
( of course, in some temples there are traditions about the idol being decorated with some special items and in some special ways. But that happens due to the Sthala Puranams, and certain revelations received by some yogis, siddhas or great Scholars in respect of that particular temple or pratishta.. Such things can never be generalized.. and such exceptions are to be effected only to the extent the ancient lore of the particular temple permit it.. )