Windmill Palm in trouble

[Dom5678]

Hey everyone I’m located in 7a. I have three windmill palms in pots which I bought in may. One of them is growing great and and it’s very healthy, one of them is not growing much but still appears healthy and one is fading away on me. 
 

For context since I replanted these guys in May i fertilized them in August when they consistently started putting out new fronds with 10-10-10 fertilizer. HOWEVER my main concern one of them may have been overwatered. I work a lot and since I live in an area where random rain storms happen I can’t always put my palms under the canopy so they have to take the rain. They have drainage holes ofc but I don’t think that’s enough. I find it strange how although each palm was bought and replanted at the same time and takes just as much water from the rain why would it be dying?

I had this issue so I dug it up to check the roots for rot. Didn’t look super bad there was some brown spots on the roots. I treated with peroxide and water then replanted in fresh soil and I’m hoping for the best. If anyone can recognize this color in the fronds or had a similar experience please let me know. I don’t want to lose this palm thanks 

 

first/second image is the palm in question

Third image is its counterpart which is the healthiest of the three 

Fourth is the roots when I dug him up to replant with new soil

[SeanK]

Fortunately these are potted. Repot the sick one and leave all three outside in a shaded area.  DON'T fertilize. 

The sick Palm will have to be flooded to eliminate air pockets in the soil. Afterwards try 2 cups of water twice a week for each plant.