A few months ago I started a number of shimpaku cuttings. Several different soils were scattered around the workshop so I tried some of each to see if it made much of a difference.
I did a similar experiment several years back and found a huge difference between soils (see “Shimpaku cuttings” for details). This year I tried bonsai soil – a 1-1-1 mix of lava, pumice and akadama – kanuma, pumice mixed with mulch, and fines from Clay King mixed with pumice.
The kanuma seemed like it would offer a good mix of air and moisture, and for the most part it did. Eight of the ten planted are doing well.
Shimpaku cuttings in kanuma
The bonsai soil performed similarly, with eight of ten surviving. The particle size was between 3/16″ and 1/4″ – what I typically consider to be a small-sized mix.
Juniper cuttings in a mix of lava, pumice and akadama
As I sift all of the soils I use before repotting, I tend to have a lot of fines lying around. I knew the drainage would be good so I tried a mix of 2 parts Clay King fines and 1 part pumice fines – approximately 1/16″ – 1/8″ in size.
Clay King fines with pumice
I was surprised to see that all of these cuttings took. I’ve used a similar mix for pine seedling cuttings for years but will now use it as a general purpose propagation mix.
What didn’t work? Pumice mixed with mulch. Just two of ten planted cuttings took – results similar to the last time I experimented with organic matter in the mix.
Poor results – pumice and mulch
I’ve used this mix for older specimens of different varieties and find it can work well, but I don’t plan to use it again for cuttings.
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