My bottom sets of leaves are turning yellow not all but some. these are 3 ladies (just showed sex today) being grown in some compost soil from my back yard. they get a ton of sun as the are in an wide open field. water just about every 2 days maybe 3 if no rain with 3/4 gallon of water each. I have used 0 added nutes just whats in the ground already. Any suggestions? the one big fan leaf thats yellow is the biggest on the plant