My sego plants own ashen on the leaves and they are curling on the ends, what do I do?

Half Dirt Half Grass?
Answers:    make sure that the bottom of the trunk of the sago in not covered near soil. These plants like to be slightly planted above ground. Second DON'T OVER WATER! They don't need like mad. I have my sprinklers set on mine for only 1 minute a daytime and 2 minutes during the hot summer months. Also you should have them planted in a mixture of cactus mix and Miracle Grow palm soil, both you can seize at Home Depot. This insures that they do not get root rot. And if you drink coffee, throw in the used coffee grounds.
Sable Palm Trees?
Are you surrounded by an area that is surrounded by drought conditions? I was having one and the same problems with my sagos after an extended period beside no rain. I began watering my sagos something like once or twice a week and the color improved. My mother also has a few small sagos. She go away for two weeks, asking me to water her flowers and garden. She said not to worry in the order of the sagos, she thought they would be ok. I didn't water them the first week, and noticed they be turning yellow. The second week, I began watering her sagos thoroughly, and their appearance enhanced as well.

Give them a good soaking once or twice a week, unless you are reception periodic rainfall. Be careful not to overwater, any, as this can rot the roots and "trunk".