I need to refresh some nasty looking cypress mulch at one of my accounts. I measured the sq. ft. at 1473. The mulch is in 2 cu. ft. bags and I need to add at least 2" to the existing stuff. How many bags do I need? Is it too early in south alabam to apply a pre-emergent? I hate to show my ignorance but what the hey......thats why we're here!