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Some of my cacti, those ones that are suposed to be green, are not looking good.

The images says better than my English so please take a look below.









Note that different species display the same symptoms. They are pale-yellowish but the very top of the plant looks better. Also, there are small dark green dots visible along the body of the plant, more evident in the parts that are more yellow.

Thanks for any clues.

They both look fine, if anything maybe a little more light will bring out the green colour.

It can also be chlorosis, deficiency in Fe (Iron) is a main cause to chlorosis.

Other nutrient deficiencies can cause chlorosis as well. The fact that the new growth has better color does point to some kind of nutrient deficiency, plants will move nutrients to the newer growth when there's a shortage. Test the pH of your mix, soil that's too acidic can reduce the uptake of nutrients.

Hi,what does the mix consist of that they are in?

hi all, thanks for replying.

I should have added some info before. These plants are under full sun (so the problem is not weak light), in clay pots with a mixture of grit, top soil and charcoal (one of my first mixes, which I'm slowly changing).

I agree that the greener tops poit to some kind of nutrient. It could be nitrogen (?), which is easly washed from the pots with constant waterings. Or Mg...or others...I'll choose one of the plants to receive some fertilizer, and compare the results.

It is interesting, however, that this color is not permanent/consistent, which is close to what Adetheproducer said. I have already noted that some days it is more visible, some days, less (I took the pictures and posted here because that day this "symptom" was more evident, and I decided to take the pictures exactly because it is not always visible).

For example, two days after posting the pictures above, I took new pictures (below), and the plants look quite better.

Some days when is colder I think it is due to the cold. But these days have been very hot. It is something to be observed yet.

the pictures of the same plants 2 days after the first pictures:

Hi Marcelo
My cacti grow in outdoor, and when the sun is very strong some plants turn yellow, but the next day they return to normal.

Could be a reaction to the strong light or the heat.

Another suggestion could be to do with the pruinose waxes on the skin surface. I find with my plants this changes texture and transparency with temperature, humidity and light throughout the year.

Thanks again for replying. I'll try to observe the correlation between this "symptom" and environmental conditions. Today is very hot and plants look nice.