If your bottom orchid leaf has turned yellow it does not necessarily mean your orchid is sick or dying. You can not prevent your bottom orchid leaves from turning yellow because this is the natural cycle of an orchid. Cut it off. Use a clean tool to avoid the possible spread of disease. Apply cinnamon (yes, the common household spice) to the area you just cut as a preventative measure against any possible infection that may try to set in.

---------- Post added at 12:35 AM ---------- Previous post was at 12:24 AM ----------

If your bottom orchid leaf has turned yellow it does not necessarily mean your orchid is sick or dying. You can not prevent your bottom orchid leaves from turning yellow because this is the natural cycle of an orchid. Cut it off. Use a clean tool to avoid the possible spread of disease. Apply cinnamon (yes, the common household spice) to the area you just cut as a preventative measure against any possible infection that may try to set in.