PS Here's the picture. I read they stop growing when their roots cannot spread out any more. Is that true?

I don't think that's a saguaro (Carnegia gigantea), but yes, it's supported by roots spreading out a bit, and if constricted in a pot it can't do that.

Here’s the same cactus 18 months later. I’m not sure if this is growing season or when to feed it, keep it dry. I’d love a little guidance. We’ve had one decent rainstorm. It sits out unprotected from sun, rain, cold, heat, whatever.

The base is beat up but what is bothering me is the yellow-ness. The pink at the base is firm. Feed now or in spring?

Gill if you see this, how is yours doing? I like the green-ness

Hi Socks, the saguaro is doing just fine thanks, I’ll go grab a pic of it shortly...just for you! Watch this space....

Gill

greenclaws - that has become a beauty - and you don´t want to take the roof off your greenhouse???

Good grief, that’s incredible! No, I definitely don’t want it to do that, lol. What a fine upstanding specimen that is.

Just been for a photo shoot in the g/h for you, not been in there for several days as we’ve been quite snowy and very cold again. I’m not wanting to get it to put on more growth, so growing it hard in this clay pot and having to contend with the U.K. climate is obviously restricting it, and I’m just fine with that as I fear that giving it better conditions it could take off.

It looks identical to my other pic above, lol.

I even managed to locate my ‘greenhouse pencil’ as in the pic above! It seems to tolerate the g/h’s low winter temps ok as I don’t put any heat in there nowadays. I was also out of the country for several weeks Nov-Dec so didn’t get the chance to install the bubble wrap this year. I just crammed all of the outdoor pots in there before my holiday hoping they would keep each other warm and safe. Things have had to fend for themselves with no visible losses so far and lows of -6C outside. The seeds were bought for one of my daughters by her now late grandad, so it holds special significance for me.....apart from being my one and only pokey, but my, those spines are so vicious believe me, it hurts for ages after a stabbing! That’s probably why I avoid the repot come to think of it? No2 daughter has yet to realise she will inherit said Saguaro in my will......!

Gill

Awww, thanks, Gill. It’s nice and green, lookin’ good to me!

I'm impressed by that homeowner's dedication to their cactus. Not too many folks would do that. Does look pretty nifty though. Imagine from the right angle it looks as though they have a green, spiny chimney. :-)

I'm sort of guessing here, but based on some very limited experience I'm wondering if it's because it had more light in later years. I've read that some cactus will be segmented, even if it's not obvious. I've grown Rainbow Cactus from seed. Here is one where the first year had pretty bad light. Then the next two years it was in the sun during the summer. I also had another one that was segmented by year.

That's just a phone photo. If you look up this cactus, or see it on grower's sites, you don't usually see this segmenting. They have fantastic shape because of uniformity of light over time, unlike mine. ! Could that be it? Now that I look at it again, I think you can see a line between year two and three, halfway up the larger half. That could be because of bad light in the winter.

There might be a segment here:

http://cactus-art.biz/schede/ECHINOCEREUS/Echinocereus_dasyacanthus/Echinocereus_dasyacanthus/Echinocereus_dasyacanthus_side_810.jpg

Here is a nicer but irrelevant photo where shape do not matter.

I never cease to be surprised by what cacti will do. This Lophophora williamsii was a regular single headed plant, until it started to bifurcate and form two growing points - now a double header.

And this Astrophytum asterias decided to adopt a mushroom shape - when it started the sides of the plant started to sink in, reminiscent of some types of rot - but it stayed firm and is now perfectly healthy - just odd.

They have both spent their entire lives outdoors under the Mediterranean sun.