Hardest cacti to grow on own root stock?

[JaneO]

There seems mixed opinion (surprise) as to what is the most difficult cactus to grow and keep alive. I have restricted this thread to those being grown on their own roots. It seems cacti are generally more tricky than succulents but I shall be interested to hear.
Thanks Jane

[CactusFanDan]

Rimacactus (Eriosyce) laui, probably. A weird plant native to Tocopilla, Chile, which receives (or more often not, in most years) an average annual rainfall of 2mm. Mats Winberg (Succseed) can't keep them going on their own roots for more than 2 years, so all his plants are grafted. Many other very experienced growers can't keep them going for much more than a year. I've gotten them to a year, but the seedlings got overrun with mites when my back was turned and they collapsed. So far this year's batch are doing well for me, growing faster than last year's batch of seedlings and developing more true to form. I'm going to keep trying until I get the hang of them. This years were sown in pots in bags (typical baggie method), in my standard cactus mix (well, standard xerophyte mix! ), in the cooler portion of my light box. If this year's batch fail, then I'll try a different approach, and so on.

Tropical cacti like Uebelmannia, Discocactus, Melocactus etc. are also considered difficult to grow in the UK, but that's largely due to the lack of heat and humidity. They need to be treated less like cacti and more like tropical plants for them to grow well. They often favour a particularly acidic soil mix too, or that seems to be the consensus of what others have said on the matter.

Then on the opposite send of the spectrum you have the cold-weather cacti, such as Echinomastus, Pediocactus, Sclerocactus and Austrocactus. These are generally awkward and trouble many experienced growers, since they're intolerant of mistakes and are usually quite moisture sensitive. They're gaining popularity and seeds are becoming more available, so they're certainly an avenue I need to explore.

Generally though, cacti are very, very simple to grow as long as you apply a bit of common growing sense, cater to the needs of the plant and don't overwater. It's far easier to overwater a cactus than it is to underwater one, therefore it's often better to err on the side of caution with watering and water less. That's generally the approach I take - water when they're thirsty, subjectively, not on a schedule. The vast majority of cacti are really easy in that sense.

I find some non-cactus succulents a bit more difficult than cacti, since I probably keep some of them too dry and/or too cold.

[DaveW]

I suppose the simple answer is those you can't grow since difficulty can vary from grower to grower as to what suits your conditions. However as Dan says many growers find certain species more difficult for them, but there's usually somebody somewhere who can grow it like a weed.

Not cacti, but decades ago we had somebody in our branch who grew carnivorous plants who went up to Kew and asked them if they had a certain species. The chap said yes we have it in tissue culture as it's rare and very hard to grow. Our member had a laugh to himself as he told us it came up as a pot weed all around his collection from self sown seeds!

A difficult plant for one person may be easy for another, also certain plants either thrive or are difficult in different countries according to their climate. Sometimes it can be as simple as finding what conditions, temperatures or composts the plant prefers and then it grows quite normally. Obviously certain conditions must be right for supposed difficult plants as otherwise they would have become extinct long ago.

[MrSlinkyDragon]

I know i am a tad late to the party here but on the topic of plants that are tricky to grow for me are the following: sonchus radicactus and tectifolus. Cant seem to keep the buggers alive! Other sonchus species, piece of cake! These two? Na they just rot off! This is despite the fact they are road side weeds!

[esp]

Then on the opposite send of the spectrum you have the cold-weather cacti, such as.. ..Austrocactus. These are generally awkward and trouble many experienced growers, since they're intolerant of mistakes and are usually quite moisture sensitive.

Are Austrocactus hard to grow? I often find them hard to germinate / get going from seed, but in my limited experience they are fine after the first year or so.

[kohinoor]

I find these native to Chile is the most problematic for me. Copiapoa laui C.hypergea.

Peacock-cactus are said to be hard on own root.But i think it's because the they are often grafted on virus infected stuck and thus accumulate a lot of different virus.

Other then cactus, the hardest species i think is Caudex Impatiens.
Like I.mirabilis and I.tuberosa. I live in subtropical regions so i first think these will be easy since they come from same climate.(Thailand and Madagascar i live in Taiwan)
I couldn't be more wrong.They are sensitive to over dry and over heat, I.tuberosa are very prone to root rot,but they die if i keep pot too dry. I.tuberosa also die immediately after re pot.
To be fair they grow reasonably fast,it just die faster.

The climate of habits is not always a good indicator for their difficulty and requirement in cultivation.

[Herts Mike]

Just goes to show. I have no problem with lauii or hypogea.

[MattGibbs]

Are you refering to copiapoa laui, or the Rimacactus (Eriosyce) laui species referred to above?

[Herts Mike]

Copiapoa. Rimacactus is another matter of course.

[ralphrmartin]

Much of what Dan says is spot on. I once argued that Glandulicactus could not be a Sclerocactus on the grounds that I could grow it, and therefore it could not be a Sclerocactus!

About the only place I would disagree (like esp) is to say that Austrocactus are not too hard to grow, although they do have quite fragile roots. I've grown a few from seed this year (see another thread for how to get the seed to germinate) but they don't seem to pose any special difficulty other than being a bit shy to flower. On the other hand, I find the tuberous roots of Peterocactus can cook if it gets too hot (grown right next to my Austrocacti).