Hi

I have just planted some bulbs: Tulips, Narcissus, Allium Moly, Allium
Ostrowskanium and Puschkinias

On the bulb packs it says that once planted I should protect the bulbs
from the cold by mulching. I am a bit confused I have been reading on
the Internet that bulbs need cold in order to develop?

Also I don't really understand the concept of mulching. Apparently it
is possible to mulch with compost but then I don't really understand
in what way that is different to burying the bulbs deeper? If I bury
the bulbs 4 inches deep and mulch with 2 inches of compost. Isn't it
pretty much the same as if I had initially buried them 6 inches deep?
At least in terms of protection from the cold?

Thanks