Moss + Swamp
To create fern in Doodle God, combine moss and swamp.
Moss+swamp
It is swamp + moss
The easiest way to say this: Weeds+Swamp (Pretty Sure)
air+seaweed=fern
fern = swamp + earth
air+seaweed=fern
grass + fern
Sorry but there is no such thing as an actual red fern. Although you could get a fern and spray-paint it red.
sun
On Alxemy, you would combine fern and earth to make a tree.
Depending on the type of fern it is, Cut it three or four times every new season. It will help the growth of the plant and make it a thicker fern.