does a dendrobium planted in lava rock need more frequent watering?

[AngelinaMaria]

This may be a dumb question but im kinda new to orchids. The most recent orchid i bought is planted in lava rock. The tag on the plant just says Den Hybrid. The lady at the nursery where i got it said that it pretty much requires similar care to Phalaenopsis but likes more light. I just wasnt sure if since its in lava rock it might need to be watered more often than my Phals that are planted in bark or moss. I've attached a couple pics of it. I just love the flowers on it! Thats what drew me to it, and it was on the 50% off table so that made it even better!