Question
I have had the apostles lily plants for many years. Only as recently as last year they still bloomed nicely but developed yellow tips and then yellow leaves.
After the blooming season I  sorted out the healthiest looking plants and repotted them. Again, they bloomed well this year but the yellow leaves reappear once more.

Please give me some advice.
Thanks, Gudrun

Answer
Gudrun,

Your walking iris or Neomarica is a beautiful plant. The yellow leaves can be caused by either too much water or too little. This plant must be kept moist but not allowed to sit in a drain tray full of water. Sitting in a drain tray full of water the roots will easily rot then the plant can no longer take up water and the leaves turn yellow. If this plant is not kept constantly lightly moist it will also get the yellow leaves you describe. Only you can decide if you have been allowing the plant to dry out too much or you have been leaving it sit with a drain tray full of water a lot. The following website has more info. Good luck!

Darlene