Even experts can and do make mistakes

Being a palm lover, a tree man, a landscaper and designer it is sometimes hard to swallow the bitter truth when you think you’re an expert with plants and you come to find out you’ve made a mistake. In my experience, I have come to learn that certain remedies work for a good majority of plants but not all.
Case in point, one of my favorite palms, the Lady Finger or Rhapis palm, is finicky. If you put this tree in the full shade, or inside a building, it will typically do very well and turn a deep dark emerald green color with shiny bright leaves.
My Rhapis palms did not do very well from the get go. I planted them underneath the willowy canopy of a Chinese elm tree on the west side of my carport as a screen. There was plenty of shade to protect them from the hot sun but the little palms were turning much more yellow with each passing day.
My first inclination was to fertilize generously. For the most part, the majority of plants I know respond well in favor of a good feeding. At this point, I spread a liberal amount of Palm Special all around the bases of the new palms. Palm Special fertilizer is a specially formulated granular fertilizer designed to give palms the raw materials they need to flourish.
Micro nutrients such as zinc, magnesium sulfate, manganese sulfate, copper and iron are formulated in this mix along with nitrogen, phosphorus and potassium. The micro nutrients are used by the palms to formulate new leaves as they push out from the center stalk of the tree.
When absorption in the root zone is poor for these trace elements due to transplant shock or a lack of roots during this phase, palms will actually pull these micro nutrients from their older or lower branches causing the existing foliage to yellow. This is also part of the reason that you don’t prune the fronds off a juvenile palm until it is completely brown and dry.
Rhapis excelsa, or Lady Finger Palms as most of us know them, originated in China. Three hundred years ago, Japanese Samurai and nobles alike collected and crossed these diminutive plants and so were born a great many cultivars. Soon multiple dwarf varieties and variegated cultivars were created making for a wide range of Rhapis palm types.
In the 1800s the Rhapis palm caught on in Europe and Great Britain. Noblemen and wealthy connoisseurs cherished these eye catching plants in their foyers and conservatories. These typical Rhapis would reach between 6 and 14 feet in height. Sometimes growing in large clumps many feet across.
Being from Asia, these trees are not frost tolerant, they do require fairly warm ambient temperature to remain healthy and enjoy well draining soil. Herein lays my problem. Thinking that the yellowing was due to fertilizer deficit or cool temperatures, I began to water my Rhapis palms like you would a Phoenix roebilini with even worse results.
Finally, I was talking with one of my guys about the problem because at this point my trees were a sickly light yellow green color and had been that way for months. His recommendation was to stop watering the trees. So we did, I turned off all the drip emitters to these palms and it was literally amazing. In less than 3 weeks, 70 to 80 percent of the foliage began to turn dark green once again.
It seems that overwatering is often more debilitating to a plant than under watering. Many things can happen to a plant that is over watered. De-nitrification, or lack of nitrogen absorption, causes a chlorophyll shortage turning it yellow. Many plants will start to root rot due to a lack of oxygen in the root zone.
Fungi and soils pathogens proliferate in sodden soils. These pathogens kill the vascular systems of the plants and cause them to either wilt, turn yellow or die depending on the severity of the moisture issue surrounding the plants in question.
So, next time your palms or plants begin to look sickly or have begun to yellow, check the soils moisture with your fingers first before you begin to water.