Question
I have giant philodendrons planted next to 2 royal palm trees.  They have black plastic around them covered with stones.  The palm trees, now 3 years old, have thrived.  The philodendron have not.  The leaves turn yellow, the plants are very small.  I'm not sure what the problem is - if it's a too much water problem or something else.

Answer
Hi Sharon, Philos like more water than palm trees.  Yellow leaves usually means not enough water.  Also, the plastic may not be letting the water to your plants.  Another thing to think about, plastic and or ground cloth causes the soil under them to rot and stink, not a heathy situation for your plants.   Happy New Year Kathy