({G} magic symbol) , plus an additional ({1} magic symbol) available if you do not control a creature with power 5 or greater available.
Steps
Activate Selvala by paying ({G} magic symbol) and tapping it, adding at least ({1} magic symbol) ({G} magic symbol) ({G} magic symbol) ({W} magic symbol) .
Activate Seedcradle Witch by paying ({2} magic symbol) ({G} magic symbol) ({W} magic symbol) , untapping Selvala and giving it +3/+3 until end of turn.