Hello:)

I'm in Central Iowa, zone 5A. I have three Thuja occidentalis 'Concessarin' Pancake Arborvitae growing well since they were planted in late Spring. At the time of planting, I added red lava rock mulch away from their crown. Yesterday, I added leaves under them, close to the crown. Should I remove the lava rock before winter? Is there a better winter mulch for my conifers? Thanks in advance.