
Certified GKH Gardening Expert
That's not easy to answer without more information on the growing conditions, soil fertility and water management. There is more than one possibility for each. The issues may be related if the plants are grown close together, or there may be different factors for the disorders.
Leaves turning yellow is usually due to nutrient deficiency. But could also be due to inadequate watering so that nutrients don't get taken up and utilized by the plant. It can also be due to root rot if the plants are getting too much water.
The century plants are also susceptible to under watering, and overwatering and root rot. There is also a potential pest problem. Consult your local extension agent for a specific diagnosis.
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