Also asparagus fern branches turning yellow, too much water or not enough water?
Spider Leaves Turning Yellow
Certified GKH Gardening Expert
Yellow leaves can happen for a number of reasons. When did you last fertilize? Too much nitrogen can eventually cause the plant to yellow and start to die. If you have not fertilized, then underwatering, lack of nutrients or a fungus may be to blame. Increase water a bit, use a balanced fertilizer on the plant and treat it with a fungicide. This should take care of the most common causes of yellowing.
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If leaves turn yellow suddenly, as opposed to yellowing slowly over time, the #1 cause in too little moisture in the soil. Try watering more, or more often. If your plants are old and heavily root-bound, up pot them a size (6" to 8", 8" to 10", etc.) - soil with too much root mass can't hold enough water for the plant. If these measures don't help, consider analyzing the soil to find out more about what's going on down there.