Hi! Years ago, we sowed seeds for what were supposed to be Saguaro cacti (Carnegiea gigantea). I'm not so sure that's what they are, however.
Here are photos of several of them - do they look like Saguaro?
Also, what's wrong with the bi-color one; have I been watering it too much?
I appreciate any help you experts have to offer! Thanks.

I found a photo of young Saguaro that look like mine, so I'm going to assume that's what they are!

I'm sorry you didn't get any answers. My guess is that you don't have small saguaros. Take a look at these images and compare them to yours. The structure is totally different.

https://www.bing.com/images/se...

I have a young Carnegiea gigantea that is several inches tall. The photos of your plants look somewhat similar to mine, but the spine length and color are different and your plants are thinner. Not sure yours are saguaros The brownish color in your last photo looks like corking, you can see it on the bottom of mine as well. It's just the plant turning woodier as it ages, completely normal.

I don't have any recent pictures on my phone, but here is a photo I took back in September when I was repotting it. I'll snap some more pictures for you tomorrow in full sunlight!

Paul, yours has the accordion folds I'm used to. Sorry I don't know the proper terminology! The saguaro can expand and contract with more water or less water.

Here are some photos...

Thanks for your input. As soon as I can get my iPhone to cooperate, I'll upload some more photos. In the meantime, I'm "borrowing" this photo from PlantBob (I found it in Plantfiles) of the baby Saguaros which I thought looked like mine.

Here are some more photos of some of my larger cacti - the largest is 5" tall. These are also grown from seeds which were labeled Carnegiea gigantea.

Ok, those do look more like it. I can see the folds now. Some of the young ones must have been too full of water and all puffed out!

mine could look different from yours as well because of our Mojave sun.

I hope no one minds my input. I don't think Paul and Susan have the same cacti. Looking at the tops, the color of the spines are completely different and the aeroles don't look the same to me either.

I swear I've seen your cactus in town here before Susan; I just can't remember what it is for the life of me.

I hope it's okay to share a link from another gardening forum, but here are some pictures of Saguro's that other folks have:
http://forums.gardenweb.com/di...

They look more like Paul's cactus IMO.

They grow so slowly that it's hard to remember what they look like as seedlings!

Thanks, everyone. I wonder whether mine look different because they're being grown indoors? Page 13 of this article compares Carnegiea gigantea grown indoors and outside: https://arizona.openrepository...

I agree that they could be something else, though. It would be nice to nail down an ID because I want to give some away (a dozen plants are too many!). I'll do some more research to see if I can figure out what they are. In the meantime, please keep chiming in!

You are welcome! it's very possible, cacti need strong sunlight to develop their spines to the fullest (the spines help to shade it from the sun). For example, I've seen chollas grown in temperate climates that are sparsely spined compared to ones grown in a hot desert climate.

Strong sunlight is in very short supply in my house, so I'm surprised the cacti have done as well as they have.

Susan, that is indeed a great accomplishment. Interestingly when seedlings, even cacti enjoy a good dose of shade, the best way to kill of young seedlings is to put them outside in the full blazing sun too quickly, but your plants are getting to the point where they shwould need to start getting a regular dose of good sun. A growth light might be something to consider.
Otherwise aside from underdeveloped spines, they will also start getting way more etiolated than they already are - stretchy and floppy from lack of enough strong light - if you look at that indoors grown young Saguaro it has a similar coloring and spine development as your plants, but it looks way more 'barrel' shaped at roughly the same size as yours.

Regarding the lack of ribs on the seedlings: many cacti (think Ferocacti, Goldenbarrels, and also Saguaros) start out without fully developed continuous ribs, but they will look knobbly in their early years. I have uploaded a pic of a 'youngish' Ferocactus emoryi where you can still see the knobbliness, but already see them transforming into ribs.



I think your seedlings could very well be Saguaros, but their greenness and the yellow-ish spines throws me off. I thought they might be etiolated golden barrel seedlings, however they do look somewhat like those indoor Saguaro seedling pictures in that article you link to, but as I noted above they are already pretty etiolated and would really need to get a lot more good light to stop that process from continuing. A growth lamp might help them show their true 'colors', but be careful when moving those plants into more light or under a growth light - they are not used to it and will probably need to be adjusted to more light/sun exposure carefully otherwise they could get scorched pretty badly and at that size, that could well be fatal.

They actually don't have a very bright future in my house in Northern Virginia, even if I put them under a grow light.

I have re-homed some, and am trying to get rid of more. If any of you are interested and it is legal for me to mail them to your state, let me know!

I took a look at the regs, and it seems okay to send houseplants to Arizona without an inspection certificate. I'm assuming that California doesn't allow any uninspected plants, but I didn't check. My daughter wants to keep some, but I would be thrilled to mail others to places where they could eventually be planted in the ground.