What should I do with this thin Dawn Redwood, how do I thicken the trunk?

[Srt8madness]

Wow did I get a lot of info on dawn redwoods in this string. I picked up about a 6' tall "amber glow" version which I guess tops out at 35'. Current trunk is a little less than 11/2". I guess from what I gather I should top trim some and concentrate on the trunk thickening while getting the roots shallower. Wasn't shopping for this, but couldn't resist a price of $37 at Lowes. They were selling out most trees to make room for Christmas crap! New to this whole hobby and love the info on here.
Thanks

1.5" is great for $37, especially for a specific cultivar. Nice find!
I wouldn't worry much about roots until you are close to the ultimate trunk thickness you want. You can nearly take off all the roots and they will regrow.

 

[Ininaatigoons]

Same with the top chop. Cristmas in October! Yes! Wait until buds start in the spring to work on roots.