The first (and most common) cause of yellowing also relates to watering: if you’re looking at limp, slightly brownish-around-the edges pale green or yellow blades, most likely the plant is getting too much water and heat and it’s simply rotting. Depending on the severity, you may be able to salvage the Cat Grass by setting it someplace it can get fresh, dry air to allow it to dry out. It’s worth a try, but it may be too late if the roots are rotted.
The second most common cause of yellowing is lack of light. If you’re seeing a bright yellow starting down by the roots, that’s the problem. This is commonly seen when you first open a shipment of the Cat Grass 3-Pack for Home Delivery. It is easily remedied by setting the pot(s) in bright but indirect sunlight for a few hours.
The third possibility is that your Cat Grass is reaching the end of its life and should be replaced.