First - I have a BC tagged in the field and want to dig it this year. It is about 20' tall, has a 10" caliper trunk, is about 6" at a height of about 36", has lots of low branches but has never been styled. It was planted about 8 years ago over a 6" tile, and has radial roots that are over 2" in diameter and go straight down as Dale and Chris mention. I am in zone 8. My questions are: when is the best time to dig this, what is the best mix to put it into, and will it push radial roots if I cut the large roots near the surface (i.e. like a cutting as I have seen some collectors post trees dug from swamps in the south with no roots what-so-ever). I was planning on digging the first of March, putting it into a Boon-ish mix with lava, pumice and turface, and planting it into a Home Depot Mason's tub that is something like 16" x 19" x 5" deep inside dimensions. Thoughts and comments?
My apologies for the delay getting to this post, and indeed I probably should wait and let those that apparently have much more experience with bald cypress than I do answer your questions...You have asked a couple very good questions here, and although I have been working with the species since the late 60's I am still learning new things every growing season...
The best time to 'collect' [which is what you are truly doing] here in the south, and particularly in the swamp areas, is mid-winter usually December and January...There are a couple reasons for this...Firstly the trees are dormant at this time of the growing season, and when removing the top and roots both it has proven to be the best [read safest] time for the tree...IF only repotting the tree and trimming back the roots [maintenance for a styled tree] it is best to wait until the leaves are beginning to harden off...The second reason is; the snakes, gators, and other critters, are also somewhat dormant, or at least much less active, at this time of the year, and the water level is usually a bit lower...
For the soil mix, the "Boon-ish mix with lava, pumice and turface" will probably work fine depending on your watering habits...These trees are extremely thirsty trees, and even though they are very 'tuff' and hardy they will very quickly die if they don't have water...The most common cause of death is a lack of water, either because of our watering habits, or because the fast growing roots have so thoroughly filled a container that it has become almost impenetrable for water...I would recommend using a heavy organic mix in the training pot or a show pot...I usually use a mix of approximately 50% mushroom compost and 50% un-sifted turface or oil-dry...If it is a 'grow' container and I am trying to achieve maximum growth, I prefer one with no drainage [although this is a much debated subject]...
Concerning "will it push radial roots if I cut the large roots near the surface", the answer is yes, IF they are kept moist...I would definitely encourage you to have a minimum of 2 inches of soil above any larger roots that are cut if you want them to put out feeder roots from the cut portion...I have even 'split' thicker roots in the past and had them to put out new roots from the cut areas...Large roots can be split horizontally and the bottom section removed to encourage lateral roots from the sides...These can also be wired to allow a bit of bending on them to achieve a more pleasing appearance, however again they must be kept well below the surface and moist until the new roots are formed and strong enough to acclimate to the drier conditions of exposure...
The Home Depot 'masons' tub would be an excellent choice in my opinion...
Second - I was going to chop it somewhere in the 36" high range (to be determined when I actually have the tree in front of me and not guessing on dimensions from what I remember), with a flat cut. I have been intrigued by the flat top cypress, as it is a much more elegant look than the powerful (yet wonderful) redwood-looking trees that Guy produces. I was then going to style the tree along the lines of something like this:
http://www.bonsai-wbff.org/nabf/newsletter2/bcarticle.htm . Thoughts and comments?
My first thoughts in reading this is; What is your term 'caliper' referring to?...Do you mean circumference or diameter?...Styling any tree is always a matter of the artist's preferences and experiences, but in my opinion it is extremely difficult to create a convincing 'flat-top' form with a tree that has a large diameter base...Unless the base tapers immediately to a smaller size then gradually to the top, it is almost impossible to achieve the appropriate ratio [in the proximity of 20:1] for a convincing mature tree...Trees which have always grown in water have a very distinctive swelling/flare at the base [I usually call them 'big-bottomed' gals]...This is true not only of the bald cypress, but also the 'willow leaf oak', the 'water elm' and the 'tupelo'...Trees with a gradual taper from a large base to apex are not best suited to the 'flat-top' form to me...I have read the linked method many times, although I have never attempted this method...If you decide to pursue this method I do hope you will keep the forum informed...There may have been others that have tried this, but I am not aware of it, and I do find it interesting that I have never been able to find any reference to how the tree has progressed since the article was written...
Regards
Behr