A bright patch of chartreuse among green plants is always welcome, except when it is not meant to be. This osteospermum has me puzzled. It looks as though it is lacking in nitrogen, which might be caused by an inability to take up nitrogen due to our highly alkaline soils, but nothing I do seems to change the color. I have added turkey compost and a solution of iron chelate to the soil but still it remains yellow. It is such a mystery because I have been growing these plants here for several years and this was a new one started from seed this year. Normally they are deep green. Something is stressing them and I'm not sure what it could be.
Here's another one in close up. Any suggestions from the gardening world.