Dear Arnold, Thank you for your reply. These trays were in a greenhouse and kept constantly damp, from moist to saturated, never been dried out. I have read that they are grown in the Netherlands and in North-France, and they also experience re-sprouting in september-october. Maybe this plant has a very short vernalization time, and when weather gets warm after a cold spell they return growing. Or maybe it was crossed with L. formosanum and L. philippinense, they are closely related, says the PBSwiki. Janos Hungary, Z5a