Loss of Pigment on leaves
This plant seems to have lost the pigment from some of its leaves. The effect appears on both sides of the leaf and in exactly the same pattern. There is no hole through the leaf. Also, some of the leaves have faded. Does anyone know what the cause of this phenomenon might be?
Some of the yellowing could be due to watering issues; too much or too little.
The soil in your container appears dry. Container plantings may need watering daily in warm conditions.
There could also be nutrient deficiency, this could cause leaf chlorosis and leaf yellowing.
A low nitrogen fertilizer can be applied in spring.
I should mention that winter cold can also discolor leaves.
I do see some spotting on the leafs. This could indicate a fungus or bacterial leaf spot disease.
Here is a link to refresh you on the care requirements.