This lily (which i may wrongly call and august lily, but is well known as a surprise lily, naked lady, resurrection lily, but still confused with an amaryllis belladonna plant) Lycoris squamigera is one of my favorites. Early spring dense foliage, which dies back (and helps keep weeds out of the flower bed) and then the spike and flower tip come up rapidly at the end of july (at least here in cincinnati it seems to be the end of july). I was curious about how fast the spike grew (which seemed very fast) and searched but in the many posts did NOT FIND a single reference to any measurements. So here is a quick and dirty estimate.
Measuring 5 stalks (not a big sample) crudely with a yardstick, at a 14 hour interval (most of it overnight) the plants can grow about one inch in 5 hours. Also, just a casual observance, the taller the spike the faster the growth, which makes sense, because there are more cells dividing in a larger spike pushing it up faster.
I will post more measurements if i have time… LOL.