We planted a large sago palm that we bought from Home Depot. After about 3 weeks, it started turning yellow. We dug it up and it was sitting in water. We need to know what to do so it doesn't die.
Sago Palm Root Rot
Certified GKH Gardening Expert
Treat root rot by removing the plant from the soil and washing the roots down with water. Then take a clean pair of shears or scissors and trim away any remaining affected roots. You may have to remove a significant amount of the root system so it will also help to prune back a 1/3 of the leaves, which gives the plant a better chance to regrow roots. If possible, dip the remaining healthy roots in a fungicide solution. After treating root rot, replant in a well-draining area.
This article should be helpful as well: https://www.gardeningknowhow.com/ornamental/trees/sago-palm/how-to-care-for-sago-palms.htm