Collected bald cypress can be grown in stagnant, oxygen depleted water because the tree's roots adapt. Submerged BC develop air passageways in the roots called aerenchyma. When the trees are not submerged, they return to growing normal root tissue. Submerge them March-October (NOLA schedule, your mileage may vary) and let them drain October-March. The tree will go back and forth developing both types of tissue over and over again. Leave the tree submerged or leave it in draining soil and the roots won't make much of a change.
A flared base and knees can be achieved with container grown BC, but that has to be the first step. If you're already developing the trunk and branches, going for a flared base and/or knees will reset your development back to the beginning. The process is simple. Alternate the flooding of the pot as mentioned above. Let the tree become root-bound. Do NOT cut on the tree at all. Knees function as a starch storage mechanism. Cut on the tree and there are no excess resources to store in the roots. You can get a nice flare from the flooding schedule, but cutting on the tree will nearly eliminate your chances of getting knees in a container.
I'm very tired, there's more to this, but that's the basics. I've got more somewhere here. Search the forum for bald cypress and you likely can't get me to shut up.
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