Put in a couple large 30 gallon royals several years back. They are healthy, thriving and probably doubled in size. Around 20-25 feet tall, ginormous base around 7 feet diameter at ground level. But there's a 4-6 inch gap at the bottom where the woody base ends and a bunch of roots are growing. I know this is a relatively normal feature with some palms, but I have the urge to pile up several wheel barrels of dirt around these. Wondering from the pros here, what is the best course of action? Mound some dirt up or leave it be? TIA, DT...

I'm not sure. Why not just mulch?

Royal palms do have a tendency to do this. Other species of palms do it too (different date palms - Phoenix spp.). It happens when they are well irrigated, and the additional moisture allows for these adventitious roots to form. You could pile soil around these exposed roots, they will continue to grow into that soil and probably grow the base even larger. You could also mulch it, pretty much the same results. Or you could just leave it as is. It comes down to aesthetics, it won't harm the tree either way. Regardless of what you decide to do, always make sure there is a large perimeter barrier of mulch or soil between the trunk/exposed roots and grass so they don't get nicked up with a string trimmer or edger.

Excellent info. Thank you Harry and Dave