Hi friends! I grew this little guy from a tiny seed! I'm so proud of him. I just noticed he appears to have yellow patches and the color generally seems paler than the usual green. What is wrong here? Thanks for your help!

That is a cute little plant - I would inspect carefully for pests sometimes certain sucking insects can cause yellow spots on a cactus, but I see no clear evidence for the presence of bugs in the picture, but some can be pretty good at hiding.

Alternatively it is some sun stress/burn, which could be caused by changes in position with regards to sun exposure - or just getting more sun or sun from a different angle - with the changing seasons. I have plants that in the middle of summer get less actual direct sun than in the fall because of lower sun angle so after looking good all summer they start looking sun stressed right around now as the lowering sun angle gives them more exposure on my front porch.

Those are my first two thoughts looking at your plant.

As to any pests: You could preventatively treat with a systemic pesticide and wipe the surfaces with some alcohol and a q-tip.

While using the q-tip you can also gently press on the plant to see how solid it currently is. It should have some give but not be squishy, which would suggest a worse problem, that I do not think is going on, but it helps to check.

And finally when did it get watered last and how cool is it already getting at night where you are at?

My thought was possibly a type of stink bug. They may be on a nearby cactus and just visiting at times. They fly readily and on small cacti they can't hide as easily and just visit. If I see yellow spots it's a tip to examine my other cacti that have more nooks and crannies to hide in. I usually find a few hiding after seeing the appearance of spots. I spray the insects directly with Safer Insecticidal Soap.

Usually that is the indication of unhealthy plants. Either from some sucking bugs, or you may have applied fertilizer/chemicals that is too strong for the plant to handle.

Hope you can identify the cause of it and eradicate the problem ASAP. Once the plant freshen up and healthy, if the yellow spots stay, then congratulations, you have a beautiful variegated cactus.

Note: If recently you ever applied any chemicals or fertilizer on it, please let us know what chemical is that