My very large mature sago just has a few brown "bristles" on the fronds from cold. I covered the sago with 3 blankets but cold got them anyway. I am not going to cut out the entire frond, just a few brown ones from cold.
Mature Sago Has a Few Brown “Bristles” From Cold
Certified GKH Gardening Expert
Once a frond goes brown, it is dead. It is best to remove them in the spring, to avoid disease and pests in the future. If only part of a frond is brown, then only remove the part that is brown. Anything that is green, leave on the plant.