Trying 100% pumice for the first time

[chris68]

Dear all,

As the title suggests I have decided to give it a go and have obtained a quantity to try. For those who have/are using it my question is have you found any problems transferring plants from an organic/inorganic mix to pure pumice? How do you find re-establishing plants as I imagine root development would be different? I have some Echinopsis hybrids and Opuntia sp. to try and may do a side by side comparison. Any tips would be appreciated.

Many thanks

[Bonsai2]

I have been using 1-3 mm Pumice and 3-5mm for the last 6 months and am pleased with the results. I also feed once per month with Maxicrop Seaweed organic plant stimulator which helps to replace any missing nutrients at 1/4 strength. I repotted a Lithops back into John Innes for a friend 2 months ago and it is now going to flower. Before repotting into Pumice, I wash any soil off the plant roots, let them dry then repot.
although the Pumice I use is advertised as being washed, I wash it again as it does contain dust.

As Pumice is more expensive than JI2 and grit, Pumice is reusable after washing which saves some money. I hope all goes well with your change of substrate.

[Chris L]

My experience of growing in pumice - you need to make sure you've got ALL the old soil off the roots. Ideally any fine roots should go too.

If I lost a plant invariably it was one that had soil and rotted roots in the pumice when I unpotted it.

Pumice roots are different than John Innes roots.

[chris68]

That was my concern about old soil! It might be that I take cuttings and root them in pumice and that is where they can stay as the roots produced will be used to the different substrate.

Thanks for the replies.

[ralphrmartin]

I would not prick out tiny cactus seedlings (smaller than 3mm say) direct into pumice - it dries out too quickly. Ones in a "standard mix" grow much more quickly. I'd transfer them to pumice once they have a good root system.

[Darren S]

I would not prick out tiny cactus seedlings (smaller than 3mm say) direct into pumice - it dries out too quickly. Ones in a "standard mix" grow much more quickly. I'd transfer them to pumice once they have a good root system.

This is good advice and I found it applies to a lesser degree to moler clay granules as well. This summer I moved on some very sad little seedlings from this into a JI based mix and they have massively increased in size and look far more likely to survive the winter.