I do not think it is a wild species of Trichocereus but it might be a nice flowering tricho hybrid.

Maybe Patrik Knoll (Cactus Jerk) can tell what it is: https://youtu.be/JERq_-WK_0g?feature=shared

I think it is a pachanoi.

Your picture isn't that sharp on my phone but the areoles don't seem to be pointing up, so I don't think it's a pc (predominant US clone).

This video explains what a PC is and its characteristics:
https://youtu.be/C6P6SEw4aG0?feature=shared

The blue one in the midle is a Browningia hertlingiana.

This paperback book by John Spain is the product of his life's study growing winter hardy cacti in cold and wet winter areas. I've met the author personally at a cactus club. He is in his 90's now and no longer gardening. He is an extremely knowledgeable person. Our Forum owner sells it on his site...

Thanks for that great slide and book, Jerry! It is a hot summer -21, so most cactuses grow well, like Stetsonia and P. pringeli. But my small T. passacana that is adapted for living on extreme high and cold altitudes, is unhappy, so i keep it in the fridge in the nights to give it some rest in lower...

During corona people have been working from home, att least in my country. Away from office they started renovate their homes and buy garden plants. It has been a boom in buying pets too. Maybe even cactuses. After Corona, when people go back to work in office they probably lose interest in their ne...

O. Humifusa, known as 'Eastern Prickly Pear', will live outside in Sweden. I get a lot of rain in New England in the spring, and they survive. We also get very cold winters. You är right👍 Humifusa is in of the best cold hardy cactuses. I hade one many years ago outside all cold winter in my balkony...

Ok. Good that it worked out for you.
Do you meassure temperatures inside the greenhouse day and night? If not, it might be good.

We have had a very sunny winter, warming my open balcony, with roof, nice in daytime, but nights are cold. Right now when writing the temperatur is -11 degr C.

I don’t have any specialist dealers near by, in fact the only one I know of is in the other end of the country. So my suppliers of cacti are the grocerystores, a couple of florists and the already mentioned Plantagen ( which is a huge garden chainstore) . You probably could order from Wermland Dese...

There are some very beautiful hybrid blooming cactuses, but some religions do not like hybrids.

Environmental conservation do not work very well when we let man made hybrids invade nature. Keep them at your home.

I do not think any cactus can handle temperatures below freezing 24 h a day for a week or two. We just finished a freezing week of eight days between -14C on some nights and 0C at the highest. They were dry, but had to stay in an unheated greenhouse. A greenhouse without two glass panes missing, as...

I had a Opuntia humifusa outdoor on balcony dry under roof but with sunlight for a whole hard scandinavian winter and it flowered the next summer. Coldest temperatures were below -20 degr C. That is an extremly hardy species and not a good example. I have killed some loved Oreocereus trolli, as I be...

Many species can stand freezing if they're dry - in your climate, a lot of cacti could be left out all winter barring an unusual cold spell, some could take anything your winter could throw at them. People often write that many cactuses can stand temperatures below freezing, but they do not tell fo...

I grow my cactuses outdoors every day of the year that have temperatures över freezing and do not have windy blows of rain entering my balcony. Ca 3 months of the year they are indors with electric light. Today I brought my Trichocereus passacana out for 15 minuter in sunshine, even thue temp was 9 ...

100% mineral substrate keeps most cactuses healthy, but if you add fertilizer to the water or substrate they still grow plump.