Nature Sense, Woodland Stride, plant growth, and command plants are fine with me.
OK then, that leaves the question of what age categories to slot them in.
I don't think we should stick command plants in the Great Wyrm slot like a Green Dragon, since it's already got quite a couple of powers there, so I'm thinking Ancient.
How about the following:
Nature Sense - Wyrmling
Woodland Stride - Very Young
plant growth - Old
command plants - Ancient
I've Updated the hit points, BAB/Grap, saves and Frightful Presence DCs.