Stuff like the roses and turrets should probs be treated like nondescript mooks: while on their own they might not pose too much of a threat, they're still not something you can just ignore and are actively resisting you. I'm fairly certain that Victoire's roses have some level of sentience, or at the very least can react to people trying to get pass/destroy it the same way an automated turret can. 

To put it in another way, stuff like roses, turrets, or hell, just nondescript mooks are there to ensure that our PC's don't just waltz up to an altar and cap it just because we could reasonably win the fight. It would at least slow us down, which may be all that's needed. One of the reasons I emphasized the Angel's numbers is so that way we always have a supply of angels to defend our altars, even if they don't fight well underwater or are particularly powerful.