Q.Christmas Palm Indoors About 9 Feet Tall Triple Stem Browning Out
Been told it might be infestation so I applied insecticidal soap once a week for two weeks Then told the tree does not have enough light – all this by nursery that sold the tree to me Their are plenty of windows surrounding the tree and now even with led grow lights on for at least 9-10 hours a day
Certified GKH Gardening Expert
You can measure the lighting around the tree to confirm. Using a PAR meter will be most accurate, but a lux meter can get you close to your ideal light target range. I'm not inclined to believe that this is the issue, though.
This looks like root suffocation. Indoor trees will suffer from this, as the soil doesn't dry out very quickly like it would outdoors. Generally, you will want your sandy soil mix to dry out almost halfway down the container within a few days, to a week at the most. It helps to ensure that your soil is well draining, which can be accomplished with a fair amound of sand and compost mixed with potting soil.
I don't recommend LED's unless you can confirm that it is a 9-12 band spectrum. You don't necessarily need infrared and ultraviolet diodes, but they do help replicate sunlight, much better. I have, yet, to find a panel that will perform as good as conventional lighting that falls below the 600 dollar mark. Once you hit the designer panels...That is when you see superiority, even, to sunlight. These are, usually, full spectrum white LED.
From here, I would treat with a fungicide. Keep a close eye on soil moisture to be sure that it has time to dry out several inches.
Keeping the humidity up will help keep it healthier, as well. Do your best to replicate its outdoor conditions, in nature.
Here are some articles that will help:
https://www.gardeningknowhow.com/special/greenhouses/grow-light-terminology.htm
https://www.gardeningknowhow.com/ornamental/trees/christmas-palm/growing-christmas-palm-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/palms-trees/sun-loving-container-palms.htm
