[spypet]

I define plant growth rate by change that is noticeable;

fast - from day to day
medium - from week to week
slow - from month to month
seasonal - varies by season or other long cycle

I consider a centimeter of stem lengthening, or
a centimeter of leaf expansion to be "noticeable".
of course, that measurement should be relative to
how tiny or massive a plant normally grows to be.

of course plant growth rates are relative to how happy
any said plant is with your tank conditions, so a medium
plant for me, could be a fast plant for you, etc.

I was just curious how others benchmark their growth rates, and if
you need to articulate more rates, such as very fast, medium slow, etc.

I wonder how PlantFinder on APC defines their growth rates.