Can you post photos of your seedlings? It would help us to comment. Most cacti seedlings grow very slowly, but after 2-3 weeks the first spines should normally be appearing and they will start to look a bit more like cacti. You can compare your plants' progress with lots of detailed descriptions of ...

1 looks like an Echinopsis / Lobivia / Acanthocalycium etc - maybe E obrepanda. There is quite variable spination with many species of Echinopsis (and related / lumped genera).

Nice progress! (And a shame about the Adeniums)
It's good to see someone growing Mammillaria mazatlanensis, it's a really nice and quite large flowered species, but doesn't seem very popular/fashionable in the UK

Lovely plant, I had one years ago.
I hope you are saving some of the seed for yourself, this plant has a reputation for being quite short lived - easy to grow and flower, but often dying quickly after being seemingly happy for a few years.

I was staying in Joshua Tree in May and saw these, I assumed they were saguaros, surely it's the most obvious iconic columnular US cactus to plant in the middle of the sidewalk?

Escobaria vivipara var. arizonica
or maybe var. vivipera?

I was trying to understand whether you watered them with dilute GA3 or (say) sprayed them with it. If the former, then it's a lot of GA3, just because the total volume of liquid in a watering is a lot more than in a spraying, for the same concentration. The decrease in wieredness would be consistent...

It looks as thpugh it needs a lot more light, the "stalks" should be compact little balls. It's too dark so they are stretching towards the light as it grows. Can you move it to a sunnier window, or outside for the rest of the summer? If you move is straight into blazing sun it can get sun...

"Postby HP22B » Fri Jan 09, 2015 2:57 pm I did one initial fertilization when making my mix using a standard plant food fertilizer at about half strength plus about 200 ppm GA3, which I suspect is the cause of their size." Could the GA3 be the cause of the weird growth? So are you saying y...

Unless it's obviously very crowded, probably leave it be. Cacti are often quite happy in slightly small pots.

8. Echinopsis oxygona - Can be almost spineless, or rather spinier than this

Maybe 1 is Echinocereus scheeri subsp. gentryi?

Thanks everyone for your reponses. I may try a further sowing of Rebutia violaciflora when ambient temps are a little cooler. Odd how Reutia albipectinata seem to be sprouting, could be the seed quality of coure, rather than species-specific requirements Good to have feedback on the Haworthias, I've...

MC#1 looks like a very etiolated Aporocactus flagelliformis. MC#2 looks like a much less etiolated version of the same thing. If I've got the id right, these can cope with quite a lot of sunlight. They are very vigorous and will need quite a bit of watering too if they are growing strongly in warm s...

A good point, Steve. All seeds are from the same supplier, obviously they will have sourced them from all over the place. Aloe ferox and Aloe glauca both have field collection numbers for the same collector, I assume they will have been wild collected, so this suggests very different germination rat...