Japanese Larch Forest Planning

I have the beginnings of an idea for a Japanese Larch forest in my head. I’ve ordered five trees each about 50cm tall. They’ll probably need a few years of growth. A couple questions:

Would it work to get new trees at varying intervals to get trees of varying sizes in the final design?

Would it work to mix different trees together? Is this something that’s commonly done? What might go well with Japanese Larch?

Mixed forest plantings are rare but people have done it. The hardest thing is finding species with comparable watering needs and overall strength.

You can get different girths of the same lot of trees by using a combination of pot size and planting media. In a small pot with a refinement soil (1-1-1 for larch) will keep them smaller. A larger pot with an organic/pumice mix will allow more growth. In the ground with a good soil and lots of organic fertilizer will result in lots of growth.

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I think I’ll skip the mixed forest for now, although I’ll be growing the trees a while before putting them together so who knows I might end up finding a nice way of mixing other types in later.

@Marty: I really like that idea, thanks for sharing! I have a question related to your comment: Does typical bonsai soil lead to slower growth? I ask, because I recently re-potted my pre-bonsais into bonsai soil thinking they’d grow faster but perhaps I made a mistake?

Anyone have an answer to my question: Does typical bonsai soil (akadama, etc.) lead to slower growth? I ask, because I recently re-potted my pre-bonsais into bonsai soil thinking they’d grow faster (more oxygen) but perhaps I made a mistake?

Akadama slows growth

Yes, a typical bonsai soil will slow growth. We want good, but controlled growth as we develop our bonsai.

The idea to get a water/oxygen balance to get good growth is right, but akadama is not the right component. The nursery trade uses decomposed bark or peat to get strong growth, but I find that the root mass is not very easy to convert over to bonsai soil from those materials. I have been using 40% 3-9 mm pumice, 40% 3-9 mm bark, and 20% bark fines for my trees in pots that I want to develop. The goal is a soil that will hold lots of nutrients for the tree, but also come part easily when I repot. This is a modification of previous mixes so I don’t have any data other than most of the trees are growing.

Okay, good to know all this! Thanks! I guess I’ll be re-potting again. I just re-potted a few days ago into bonsai soil; they should be OK to quickly follow-up with a re-pot into this type of soil, right? I doubt they would have grown too many roots to make this difficult on them?

I received composted bark today, this one: https://www.amazon.co.uk/gp/product/B00WUQCPXM/
I have some pumice, which is probably too coarse as I got it for the bottom layer. Would this be good to mix with the above? https://www.amazon.co.uk/Horticultural-Pumice-2-4mm-dried-PureGrow®/dp/B08YTKHLGN/

Then I’d mix 60% bark, 40% pumice?

Change that, I found much cheaper pumice from a more reputable source: https://www.kaizenbonsai.com/pumice-medium-size-horticultural-media-bonsai-succulent-plant-alpine-soil

You can probably do a repot again since they are small and have not grown too many roots. However, they will have started to grow new roots and you will undoubtedly break off some of those. Or you can wait a year and pot the already improved roots system in the stronger growing media and not rush things.

I have two flats of Japanese maple seedlings that are entering their third growing season. They are planted in a mix of 1-3 mm pumice and potting soil. It works well for starting seeds, but is not that good for promoting growth. I should really repot them into the coarser mix this year, but life got hectic and they are going to sit in the finer mix for another year since I have to repot some more mature trees rather than 400 seedlings. Yes, I lose a year of development, particularly of the nebari, but I am in it for the long game - 1 year out of 10 - 20 to start to look like a bonsai is not that much. BTW I will not be developing all of them into bosnai.

I’m getting a large (about 3m) tree tomorrow. Would you use the same soil mix? Given the pot size, it seems expensive.

Soil mix is somewhat based on what you want to do. If you are getting a 3m tree I assume that means you are planning on chopping it down to make it more manageable? If so, then you shouldn’t change the soil at all. Do the chop and then let the tree recover and maybe repot it next year.