It needs much more light.

The potting mix may be holding too much moisture, as well.

Does the container have drainage?

Josh

Yes the pot is one of those "self watering", I try not to water it too much but the soil is usually very dry. Can't seem to find the right amount of water to make it happy. I can try more sunlight.

Yes, get it into as much sunlight as possible.

Can you empty the water reservoir of the pot? If so, empty it immediately.

These trees thrive in a porous potting mix that is regularly flooded and then allowed to dry. This encourages a very healthy root-mass. In a peaty mix, the root-systems are almost always weak and have a hard time supporting a vital plant.

Josh

I have found those self-watering pots difficult to regulate, because they retain too much water. If it were me, I'd repot in a regular pot and toss the self-watered.

Is that a 4" pot? Hard to tell. These plants have very small root balls compared to other plants. I think it would do better in a smallest pot to fit snugly. Then don't mess around with it too much afterwards, just leave it be and keep it watered.

Sara, these plants actually have extensive root-balls, when they're healthy. The small root-balls are typically the result of an overly moisture-retentive potting mix, where roots in the saturated levels of the mix continuously die off. This gives the impression of a small root-ball.

When I re-pot my Pachira, the pot is completely filled with a vital root-mass.

To give a more detailed story, I originally had this plant in a pot that was about half the size, maybe 10 in diameter which was flourishing quickly and almost too fast for what the main shoots were able to support. But then it started portraying these pictured features of wilting, weak leaves and unsupportive tall shoots. I went to the local store I originally bought the plant from and the lady seemed a bit uninformed but suggested I try transplanting it to a bigger pot with organic soil mixed with sand to help retain moisture. So now it is in a much bigger "self watering" pot (which I never use the reservoir because I don't necessarily trust it, I just feel into the soil to try to judge how much water to give it), with a soil/sand mixture. And ever since I transplanted it with these recommendations about 6+ months ago, it has never seemed to get better....

So hopefully it will be alright with the sand soil mix for the rest of winter. Do you suggest I repot in a smaller size pot or just keep the same size and just do a new potting mix without sand?

I would pot it down, indeed. Then, pot it back up in size, the following year...once it has established a strong root-system. In the meantime, start planning your new mix. If you can make your own mix, that would be best. However, if you're limited to purchasing mixes, I'd recommend a fine-grade "Orchid Mix" that is primarily small fir bark (less than 1/2 inch diameter pieces of bark). To this, you can add a pinch of potting mix, and an extra pinch of perlite. This makes a decent "off the shelf" mix that offers durability, drainage, and aeration, so that you can water and fertilize without fear of root rot.

Josh

Keeping the Pachira in more light has caused a lot of leaves to almost dry up - they look blanched and crumble upon touching (I removed most of them but you can see some of the partially affected leaves). Although there is still some new growth on top. Are the old leaves that are drying out being sensitive to the extra lighting?

Meredith, there is something else happening. Only full sun will actually burn leaves...I've done it! Pachira can handle outdoor shade, even sun if acclimated. They are tropical wetland trees, after all.

What sort of mix, and how large a container are you using?

Josh

It was getting very direct sunlight right in front of the window. That info is in my previous comments

Where did you mention it was right in front of a window? Can't find that in your previous comments.

Regardless, it should be smack up against the brightest window you can offer. These plants, in my experience, do not burn indoors. Outdoor shade is brighter than sunny indoor windows. Only outdoor sun will burn the leaves.

Josh