Fast germination.

Hello, as far as I am aware, the hover fly is attracted to the marrigold flower and it's a big bully fly that beats all the nasty black/white/aphid flys from your veggies, I think it also aids pollination, so all round beneficial.  

My Greyhound cabbages sprouted today, after just 6 days. Earlier batch took nearly 2 weeks.
Also a solitary tomato (one of 18!) popped its head up today - planted 04/03.
It's only my first proper season - hadn't ever touched a seed til last August - but I'm already finding that it's true what the experts here say - things planted later do catch up with the earlier plantings, which just sorta lie in a coma til the sun comes out.

Marigolds & cress planted Tuesday sprouted in 24 hours.

(Not that I doubted the experts here BTW, but good to learn for myself via trial & error - it sinks in that way!   )