Growth stages
From a 2 mm seed to a 3-metre blade in five months.
Five months, seed to blade
Kelp is a winter crop. It grows through the coldest months of the year, when nothing else in the ocean is, and it is done before summer warms the water.
month stage dec spore settled jan germlings, 2 mm feb visible blades, 10 cm mar rapid growth, 1 m+ apr full length, 2–3 m may harvest
The trick
Kelp grows fastest right before harvest. Wait too long and the blades thin and start to tear. The telemetry — not the calendar — decides the day the boats go out.