Yes it is okay to pluck ,cut or boil any herbs as tea, medicine or you want other spiritual help using the elementals of plants; provided you follow the rules.
Like you rightly observed, plants are alive and indeed they are the bodies of elementals. They are governed by bodies of angels
responsible for each of the plants and the Divine Mother also rule as their Mother. they feel pain when cut or plucked just as you would
when injured.
Therefore, ensure you pray the Divine Mother to entreat the elemental/s of any plant before cutting or plucking them. You make this supplications to the Mother in other to be permitted to access and take from the plant. That way, you will receive the cooperation of the
plant and the plant will yield all its properties for your benefit .

Study the book Igneous Rose. https://glorian.org/books/igneous-rose