I’m getting prepped to pot two bald cypress from grow pots into their bonsai pots, this spring and wanted to sanity-check soil ratios with the group.
For context, both trees are currently in 100% organic soil in grow containers. They’re healthy and vigorous. This move is a transition into refinement, not development.
I already have a base mix that’s 50% lava rock / 50% fine pine bark, fully mixed. The bonsai pots are about 4" deep, and the trees are on an automatic watering system.
My thinking is to keep oxygen as the priority in a shallow pot, but add just enough organic fines to help with moisture and nutrient holding during the transition out of straight organic soil.
Right now I’m considering adding a small amount of peat-based potting mix to the existing lava/bark mix, somewhere in the range of:
• 6–7 parts lava/bark mix : 1 part potting mix
That would keep peat around ~12–15% of the total, with the pine bark doing most of the “mulch” work structurally.
For those of you refining bald cypress in shallow pots — especially in humid or warm climates — does this feel reasonable for a transition mix?
Would you go leaner on the peat, skip it entirely, or substitute?
Appreciate any firsthand experience, especially long-term results in bonsai pots.
I do not know anything about Bald Cypress but I just finished a Mirai Academy Video on Elongating Species 101- Deciduous Conifer-Example Bald Cypress and its says 100% Akadama particle size 1/16-1/4 inch (2-6 mm) for soil. You might check it out. Again this would be totally new tree type for me just trying to pass info along to you as literally I just viewed it 20 minutes ago.
I would get rid of the organic in the bonsai pot and go to a fully inorganic mix. I have found that the organic material can lead to root rot in a bonsai pot. Ryan uses 100% akadama as stated above, but that can be expensive. A mix of equal parts lava, pumice, and akadama is used by Mirai for pines and such. That mix is used very successfully by many folks who follow Boon Manakitivipart foo all of thier trees including bald cypress. I use a mix of 3 parts akadama and 1 part pumice for bald cypress and other high water mobility trees. Another option is to treat it like a collected tree and plant in 100% pumice, particularly if you have to do a lot of root work.
I just saw you Tuesday night! You have any questions, I recommend Randy Bennett’s book on bald cypress. Otherwise, 75% pinebark 25% lava. If you think that’s too organic, you can go 1/3 pine bark, 1/3 pumice, 1/3 lava. If you’re out of anything, call me and your wife’s aunt can come by and pick it up from my house. I’m fully stocked on pumice and lava rock (red and black).
Hey Bill! Thank you! I am definitely going to use your 50/50 mix. In the back of my mind I was thinking that it was not organic enough. Randy’s suggestion in the book says no less than 80% mulch and 20% aggregate. That is why in the back of my mind I should add more organic to the 50/50 mix. I still have plenty. Thoughts?