What are they missing?
Indoor Plants Ends of Leaves Yellowing
Certified GKH Gardening Expert
This can be a number of things:
It could be lacking light, or being over-watered.
It could be lacking nutrients, and depending on where the yellowing occurs, can be a number of deficiencies. Make sure you fertilize every few months with an all purpose fertilizer.
It could also be a pH issue. use dolomitic lime to adjust pH.
It could also be bacterial or fungal. Use wettable sulfur in the soil to control this.