I am also new to dawn redwoods, I recently bought a thin sapling online and I am trying to keep it alive at the moment. As far as I understand:
- They are really fast growers
- They tend to develop straight trunks without taper.
- They backbud very well
- Since they tend to grow upright, cascade style may be inappropriate for styling. Best suitable forms are forest, formal and informal upright.
- They also grow roots very quickly and they do not care about a wet soil.
I am planning to get an informal upright with my baby sapling.
My first step will be to repot it and do the initial rootwork next early spring. I will trim the roots to achieve a wide spreading radial rootbase, cut the roots that are growing perpendicular deep into the ground and keep the ones that are lateral. I will also cut the roots that are very thick compared to the average and the ones that can not be lined in a direct angle to the trunk. (the ones with a circling angle). If you did not do any rootwork until now, maybe this can be the first step.
After that, I will let the tree grow freely another season (until late winter or early spring) and than focus on developing the taper.
Considering that dawn redwood is a fast growing species, my choice for my sapling will be the clip and grow method for achieving trunk taper, which is slower but will end up with a better quality. So, there will be frequent but smaller cuts, not bigger than one or two centimeters maybe.
But if you want a quicker progress you can choose the chop and grow method.
Those strategies are very well described in the video below by
@leatherback .
