How long has it been in that pot?

@Kara About 1.5 years.

This plant had originally rotted when it was first purchased in about a 2 gallon-sized container. I had to keep cutting until it was down to about two inches in length, with one leaf left. :) It was the best "save" I have had to date.

@cactusmcharris okay, so totally normal, and there would not be a reason to water more often?

Spot on.

Here is a photo of this plant earlier in its life. Note how it is green everywhere. I am not happy with how the current plant's leaves look starved (either for water or some nutrient). Is the yellowing maybe a sign of underwatering? I am gunshy to water this too often since I nearly lost it to root rot when I first bought it.

I would suspect that's (1) a different time of the year and (2) there was more rain and less sun available.

I told you why the yellowing is occurring. Is there a reason you don't think that my explanation is the answer with your particular plant?

Cotyledons will look a little starved for the next several months, then they'll start going back to the lush life. It's a natural fact.

If you learn about your plants (and where they come from / when the predominant rains come) it will help with the anxieties of an over-cautious gardener. I was one, and perhaps still am.

@cactusmcharris Time of year is certainly important. Summer water-stresses any pot in the direct sun that uses gritty mix. But I think there is also a clue in the size of the original pot. I think that original pot probably had more water available to the plant because the roots would be right to the bottom of the pot, into the perched water table. The new pot is enormous and deep, and I am wondering if maybe the roots are not getting down to the bottom. The part of the soil where the roots are developing may just dry out very rapidly.

I am simply wondering if it is worth the risk to run an experiment and water three times a week instead of once.

' Summer water-stresses any pot in the direct sun that uses gritty mix. '

Aye - there's your problem, lad (I'm guessing you're male). Don't use gritty mix, but use a gritty mix.

3x a week, now, when the plant's going into semi-dormancy, is too much (refer back to learning where the plant comes from and when its watering is generally received).

And I just now read Kara's question and your answer. Try repotting it into fresh soil (let the plant's rootball determine whether you need to upsize your pot).

@cactusmcharris So if you do not like the gritty mix for cotyledons, then what soil mix do you prefer?

Your point on this being the down season is that cotyledons are winter bloomers, similar to aeoniums? I have other varieties of cotyledon that seem to be thriving, also in the gritty mix, and also in full sun. Those are similar size, but smaller containers.

The container this plant is in is very large. There is no way the roots outgrew that pot.

50% pumice and 50% sieved Supersoil always worked quite well for most plants.

I wanted to show some photos of my other cotyledons to see how they differ from the subject plant.

The first photo shows one of my favorites in December 2019, clearly in season and quite green.

The second photo shows the same plant now in summer. While there is a slightly yellow leaf, the plant is thriving in the gritty mix and is clearly showing signs of new growth as well.

The third photo shows two baby cotyledons, both of which have been showing explosive growth in the gritty mix, after taking about four months to settle in and growing roots.

The baby plants are certainly in an oversized container. Maybe their growth is just because of their young age. But the adult plant with the two photos below clearly is not going into a major dormancy. I just wonder if that is because the smaller pot size puts some of the roots into a wetter area of the pot, and it never gets totally dry. To contrast, the subject plant is in a huge container and it would not surprise me if after just three days in full sun the roots were totally dry. Might that explain why the plant is showing a little more stress than the others?

So this gets strange. All the yellow leaves fell off the plant, and now it started a cycle of voracious new growth. Leaves are popping up all along the stems as well as in the top sections of leaves. The only thing that changed here is I started to fertilize the plant. I water about twice a week.