When do I use the gerundive vs. participle forms of a verb in Latin?
I think that your question will become a lot clearer when you realize that the gerundive is a participle: specifically, it is the future passive participle.
This is thus not a question of choosing between a gerundive and a participle, but rather choosing which participle (tense and voice) to use. Here is a brief overview of the kinds of participles of amare (to love):
- Present active: amans, -ntis
- mater amans: "a loving mother" or "a mother who loves"
- Future active: amaturus, -i
- mater amatura: "a mother who is about to love"
- Perfect passive: amatus, -i (N.B. this has an active meaning with deponent verbs)
- mater amata: "a beloved mother" or "a mother who was loved"
- Future passive: amandus, -i
- mater amanda: "a mother who shall be loved"
Note that this future passive meaning most often conveys a sense of obligation, i.e. "a mother to be loved" = "a mother who should be loved."
If you provide further details about your use case, I can specify further, but as you see there is a pretty clear distinction between each participial form.