Our house is on an inclined lot and we have a stone retaining wall in front of our house that stands 3-4 feet high. The stone wall comes out 4-5 feet from the front of our home and this is what makes up our front flower beds. When the builder built our house they filled this area with sand and topped it off with mulch. The plants that were planted in the flowers beds dont seem to be getting enough water. I had a couple of landscapers come out and they gave bids to pull the existing plants and dig 1-2 feet of the sand out of the flowers beds and fill with Pro Bedding Dirt. They said that sand retains no water and can be harmful to the plants. This soil for the beds is full of sandy loam (the silly putty looking clay). Based on what these landscapers are telling me, is this necessary? The bids they gave to do this were real high that is why I am asking. I can post pictures if you need me to. Thanks for your help.