pure pumice?

[MikeDom]

The plant in my collection that has caused me most grief is this particular Larryleachia, I can sympathise with anyone that has tried to grow them. He is 7 years old and started as a 2cm ball. I have a couple of plants and this is a picture of this particular one last spring.

Last summer I turfed him out of his pot because he was very soft and would not respond to watering, but the root system was very healthy. Note he is planted in 75% cat litter and 25% JI.

It turns out he is now a winter grower, takes temperatures down to 4 Deg C when wet, firms up in November and has started putting out flower buds. Has been watered once a fortnight since November. No amount of watering during summer would elicit a growing response, didn't like being put in partial shade either. It's the first year I've had a problem with him, previously he has grown quite happily during summer. The other one is carrying on as a summer grower.

Everything the text book tells you not to do, and I believe his converting to winter growing must be a reversion ....

This is what he looks like today. Very difficult to root cuttings apparently, otherwise I'd pull off a few.

[Herts Mike]

Fascinating! I acquired a small cactiforme in autumn and have watered it 3 times this winter. Each time it has reacted well and firmed up.

[Herts Mike]

Temperamental. Can't be a he then.

[Tina]

LOVELY, yours has had sunburn too I have a monstrose one that seems to burn every year but it's a tough plant, not grown well by me.

[MikeDom]

Temperamental. Can't be a he then.

I think 'he' as knows what he wants to do and sticks to it

[Tina]

Must be a he, stubborn for no reason .
Could you do this as a new thread please then we can ask more questions on growing this challenging specie

[Ospreywatcher]

I purchased a 25L bag of crushed lava rock but haven't started repotting yet, does anyone know if it is as good as pumice?

[Paul D]

I purchased a 25L bag of crushed lava rock but haven't started repotting yet, does anyone know if it is as good as pumice?

Funnily enough I had a discussion with a fellow member about this at our last branch meeting in Aberdeen on Thursday. I did the same as you and bought some "lava rock" (also known as scoria) which is being sold on Amazon as pumice. I also bought some proper pumice from Specialist Aggregates. So I've been doing a bit of researching to find out the differences.
Plenty of people seem to use scoria, especially in the USA, also including mixing it with pumice, but it seems to be acknowledged as not as good as pumice. It is a bit heavier, not so quick to dry out, has more dust, and has a different mineral content than pumice. I'm going to do a trial comparison by potting seedlings into (a) pure pumice, (b) pure scoria, (c) a mix of the two and (d) my own original mix of JI, cat litter, grit and perlite. I will report back in a couple of years

[MikeDom]

I am experimenting this year with growing Pseudolithos in volcanic 'Lapillo'. Happened to find a bag I purchased a few years ago and thought I'd give it a try. Mixed with about 20% coarse sand.

From the retailer: "It is formed during violent volcanic eruptions and is the term used for small particles (2-65mm) that explode into the atmosphere and cool on their descent back to earth. This violent formation creates a fine honeycomb structure which is perfect for cultivating plants.

The porosity of the material averages 50-60% by volume. Lapillo has high levels of iron, magnesium and other minerals vital to plant health. 100% frost proof, Lapillo can be sieved out and reused many times. We recommend using Lapillo in conjunction with other soil products like Akadama, Bark , Moler, Pumice. Mix with other products to create a free draining, long lasting mineral rich growing environment"

Widely used in bonsai soil mixes, so why not succulent mixes? If we don't experiment, how do we move on in life?

Though I won't be testing whether it is frost proof with the Pseudolithos growing in it.

[Ospreywatcher]

The aggregate I purchased from Amazon was actually listed as crushed lava rock, not pumice. I did not know that Ikea sold pumice and will certainly be making a 15 mile trip to my nearest store to purchase a few bags. Now getting geared up to do a mass repotting trying different mixtures and will be keeping an eye open for more Tesco pink cat litter in case they have started to stock it again!