Brussel Sprouts prefer cool weather and rich soil. Approximately 240 seeds / gram.
Hints:

Start indoors.

Transplant 45 cm [18"] apart in rows 75 cm [30"] apart.

Rotate to a new location each year.

When sprouts form, remove lower leaves to seat heads.

Brussel Sprouts - Long Island Improved - 90 days. Round tight heads on a comparatively dwarf brussel sprouts. 60 cm [2"] tall, with firm cabbage like sprouts, maturing over several weeks.