Shimpaku slow growth in pure pumice?

[ptien]

I have a couple of shimpaku in 100% pumice (3-6mm) and they all grow slowly with very little extensions. Yesterday when I pulled them out I saw their roots barely grow even after more than a year.
On the contrary my black pines and hinoki seem to do extremely well in pure pumice and have put a lot of growth so I'm not sure why?
Should I change to Bonsaify mix (perlite and coco peat) for these shimpaku?

 

[Bonsai Nut]

I keep most of my shimpakus in 100% pumice and they do fine. The key is to make sure they are getting enough fertilizer.

 

[Russ1]

I grow mine in 80/20 Perlite/Coco.. and second the Fertilizer.

 

[darzuo]

I've grown shimpakus in pure pumice and haven't noticed poor rooting. What size trees are they? Could be fertilizer or watering issue, or maybe they're not secured enough into the pots? Hard to tell without seeing, but it probably isnt the substrate choice thats the problem.

 

[Brian Van Fleet]

Junipers just take a while to build up a head of steam.

 

[Orion_metalhead]

Share some photos!

I have one shimpaku in pure pumice and it grew great this year with some nice long extension growth. My older shimpaku in turface/perlite/pine did not grow nearly as much even though it was established for a year in the pot.

 

[ptien]

They are 2-3 years old cuttings and some 2-3cm diameter trunk. Organic fertilizer each month and foliar spay every 2 weeks.
I add a layer of sphagnum moss due to the hot climate.

 

[Orion_metalhead]

The foliage is a bit sparse, probably recovering from rooting and typical young-cutting stuff. As we know, juniper strength is in the foliage. I think that after a year or so, these will take off. Just let them grow, no trimming or pruning back for a while until you get long runners. They look very healthy though. I think it's like Brian said, they just need time to grow and pick up some momentum.

 

[ptien]

The foliage is a bit sparse, probably recovering from rooting and typical young-cutting stuff. As we know, juniper strength is in the foliage. I think that after a year or so, these will take off. Just let them grow, no trimming or pruning back for a while until you get long runners. They look very healthy though. I think it's like Brian said, they just need time to grow and pick up some momentum.

Thanks, they put some growth and backbud after a year but almost no root growth. I can pull them out of the pot easily. is it normal for shimpaku?
I'm thinking to switch over to perlite + coco as pure pumice dry out too fast in my climate.

 

[Shibui]

I cannot manage many species in inorganic mixes. All species do better in a mix with some water retention for me but I also agree that juniper chinensis vars seem to take a year or more to get going after transplant.

It helps us help you if you add a location to your profile. That lets us make some inferences about the time of year and your climate compared to ours.

 

[Bonsai Nut]

Junipers just take a while to build up a head of steam.

I want to second this comment. When you repot a juniper it seems to take a year to get re-established. For the first year year it will sit and look healthy, but it doesn't really start to throw new foliage extensions until year two. If you repot every year, your junipers may never really take off.