ID Help for Mini Cacti and a couple of other questions.

[Mooly]

Hi folks, my first post on here (on any gardening forum come to that) and I'm seeking help identifying exactly what these three mini cacti are. They were bought on impulse from a local household chain store and to my untrained eye looked quite healthy. From what little I have picked up so far I have resisted the urge to water even though the (peat ?) based compost is 100% dry and shrinking from the pot edges. I live in northern England and placed them on an east facing windowsill. Temperatures at night on the sill are around 12C but even now in late January can reach the mid 20's for an hour or so with a little sun.

So my initial questions are,
1/ What are they ?
2/ When should I begin watering.
3/ The limited instructions that came with them suggest they are OK in these pots for 12-24 months. If I considered repotting (perhaps all in a single bowl) when would be the best time ?

And thanks for reading.

[adetheproducer]

Number one looks like mammillaria bombycina but I could be wrong.

[cactidan]

Yes id agree with Mammillaria bombycina, not 100% on the 2nd, maybe some type of trichocereus, but the last one looks like a Mammillaria karwinskiana form. They all look good, but will almost certainly be in just peat which is not great for growing them at home. So will appreciate being repottedinto a coarser mix and probably larger pots too.

[Mooly]

That's great, and thanks for the quick id on these, it will give me something to look up and research. If I did repot these would there be any "best time" to do this, perhaps even before they start growing and require watering.

[cactidan]

You can repot now, I would advise taking them out of the pots, removing the peat around they're roots. This may be rock hard, depends on how long ago they were last watered, but if it is not to worry, just break it up with fingers and shake what you can off the roots. Some people do go to great lengths to wash every scrap off, I don't personally, as long as the roots are freed up and the nearly all the peat is gone then I'm happy. you can leave them to one side to let any broken roots heal (there will almost inevitably be some). The next thing is your soil mix, there are lots of options here, the important thing is that it is free draining, not too dense and uniform throughout the pot. The small bags of cactus compost that are sold are ok'ish but usually don't have enough grit in them. As for pots, I'm assuming those are 2" pts they are in, I would move them into 3" ones.

[greenknight]

I agree with cactidan, but it should be mentioned that Trichocereus is now lumped in with Echinopsis, and that's where you'll find them in the CactiGuide galleries. The name Trichocereus is still commonly used in the nursery trade, though. IDs can be problematic with them - not only are they quite variable, but they've been extensively hybridized.

[Mooly]

Yes, they are indeed 2" pots and I would bet the peat is rock hard to as you say. It certainly looks and feels that way from the top. I might look out for a suitable bowl actually, rather than individual pots so I'll have to keep my eyes open and see what's available. Probably trying to run before I can walk with all this but I quite fancy a bowl type display perhaps with a slightly larger cactus in the centre.

Thanks for the further id info greenknight, when I first started looking (before all your id's) I hadn't imagined there were so many sub varieties.

[KittieKAT]

Just make sure the bowl or new pot has a few holes in the bottom for drainage or they will rott. Goodluck

[Mooly]

Thanks KittieKAT. I've just this minute finished repotting them and in the end went for separate slightly larger pots. I wimped out and for convenience used some premixed cacti compost from a local supplier but I also added some horticultural grit, same as you can see on the surface. I shall wait a week or so before attempting to water them. The roots seemed quite good and filled the old smaller pots. Managed to get most of the compost off two of them and perhaps 80% of it off the third. Just have to see how they do now.

[greenknight]

Looks good. In those pots they really should be good for 12 - 24 months. Appears you got the right kind of stuff to add to the mix, that should work just fine.

I would wait more than a week before watering them - this is the dormant season, when you wouldn't give them water more than once a month normally. I assume the potting mix is somewhat damp, you could just wait until Spring.

[Mooly]

Thanks. Yes, the mix was very slightly 'damp', that is damp as in not quite totally dry, and so I was wondering about watering. The original stuff in the pots looked as though it hadn't seen moisture for several weeks but then again I suppose that is at it should be. From what I have gathered on here, slight shrinkage and wrinkling (there is none at the moment) would be a sign that a drink is in order. I'll resist the urge to water them for the time being then, certainly for immediate future.

[greenknight]

If they were kept at around 10C they could definitely go without water, but since it's a little warmer where they are you might want to give them a little water in 3 or 4 weeks - especially if there's much sunny weather. When Spring arrives (go by the weather rather than the date), give them a thorough watering. You should get them as close to the glass as possible then, and open the curtain - they're going to need more light!

[Mooly]

You've pre-emptied on of my next questions which was to ask whether the first 'proper' watering should be a thorough one. Something that bothers me (even now with them on a sunny sill) is that the pot temperatures will get pretty high. Is that a problem for the roots ? In summer that would probably be in the high 40's (C) at a guess.

[DaveW]

You could always double pot by putting the pot inside another slightly larger pot to keep the sun off the internal pot the plant is in.

Video here, but would not bother with the moss, just let the air circulate between the two pots with the internal pot just resting on top of the gravel:-

https://www.youtube.com/watch?v=O5zVYno7b9U" onclick="window.open(this.href);return false;

[Mooly]

Thanks Dave. That's a good idea, its something I would not have thought of.