I just saw a new dragon in the marketplace called an Ash dragon. How do I breed one, and what is the breeding time?
Per the Dragonvale Wiki you can breed an Ash Dragon by breeding a Plant Dragon with a Lightning Dragon, or by breeding any plant hybrid with any lightning hybrid.
The breeding time is 6 hours, or 4 hours 48 minutes with the improved breeding cave/EBI. It is not a limited dragon.