is there a set amount of xp for each nectar?

i assume the current month's seasonal flower will give more points compared to regular nectar, kinda like how they give more power to your pikmin when you send them off to mushrooms. i'm mostly wondering if there's some sort of middle ground for past seasonals and the points they give when you feed them to your pikmin. are past seasonals still worth more than regular nectar?

i usually save any past seasonal nectar for the next year, but with getting past seasonals from mushrooms and such, i'd like to know the benefit of giving them that nectar outside of waiting for the next year to come :)