Sometimes, when young, they need a bit of encouragement to grow upward. After they get around 3 or 4 feet (roughly) they finally get the idea.

tj

I have three of them. I generally tie a piece of slender bamboo to the new growth when it pops so that it grow upright and straight - as tj says, until it gets the idea! I have never staked the entire plant on any of them. Great tree - the quintessential 'Whoville' tree in my mind!
Sara

If staked for height it will grow that way.

Once the stake or vertical tie is removed and the cultivar is left to free range it will wonder and take to its own choosing as to what it wants to do.

It is not programed to grow vertical and only gets the idea from you. Take the restraints off and the game is over.

I'll show you tomorrow.

Davesconifers

this is one ... that has every intention of growing straight UP ...

once it is taught.. that it is no longer a branch ... [ask if you dont understand this part]

be careful on FF's suggestion ..... new growth can snap off very easily.. been there.. done that... but wait a few days too long.. and they harden off and you will never straighten them out ...

ken

Ken is oh so right...delicate fingers are a must when doing this, as well as very supple ties.

Sara

Yes and I am so wrong.

I had it confused with another.

Dave

Once that leader is vertical all on its own, no more need to stake.

Dax