Rather than describing seasonality abstractly, it helps to
follow one plant closely through an entire year. We'll use
nettle (nokkonen) as our case study, since it's common,
easy to find, and changes dramatically across its cycle.

The first nettle shoots push up from the same rootstock that
overwintered underground, often before most other plants
have woken up. These early leaves are the most tender of
the whole year, and the ones most foragers prize.

As days lengthen, nettle grows quickly, putting up taller stems
and more leaves. The sting becomes more pronounced as the plant
matures, and the leaves, while still usable, become slightly
tougher than the very first spring growth.

Nettle produces small, inconspicuous greenish flower clusters
in early summer. Many foragers consider the plant past its
best for eating once flowering begins, as the leaves develop
gritty calcium oxalate crystals that become more pronounced.

The flowers develop into small seeds through mid and late summer.
The plant's energy shifts toward seed production rather than
leaf growth, and the stems become noticeably tougher and more fibrous.

As temperatures drop, the above-ground growth yellows, browns,
and eventually collapses entirely. The plant's energy has
already retreated underground into its root system,
where it will overwinter.

Most perennial plants follow some version of this pattern —
emergence, growth, flowering, seeding, dying back, dormancy —
though the timing and visible drama of each stage varies
considerably by species. Once you've watched one plant closely
through a full year, you'll start noticing the same underlying
pattern in others.