Pruning a flowering dogwood should be approached in the same manner one does a magnolia......as lightly and as infrequently as possible. Two tree species that react poorly to pruning by producing excessive epicormic growth that is unattractive and congestive. Where it is recommended to limit pruning to no more than 1/4 to 1/3 canopy reduction, for dogwoods and magnolias, that drops down to only 10%.

I'd give the tree a couple of years in the ground to establish before ANY pruning is considered. Lower branching should never be removed too early. It helps to develop trunk girth and speed root development and establishment.

If I'm looking to encourage a top-growth pattern, how soon should I begin pruning the bottom branches

==>>> no..no..no.. you dont cut pieces off to stimulate growth ...

every leaf is an energy making machine ... needed to grow a mature root mas.. to get the plant to grow to specs ...

so for the next 2 or 3 years.. no pruning.. period ...

thereafter.. the plant will SHOW you its growth pattern..and you can SELECTIVELY encourage it in any direction you wish ....

and dont bother wasting time nor money on fert.. shrubs simply dont need such ..

ken

ps: i would not winter prune in my ground freeze MI .. and since you didnt tell us where you are.. we cant tell you the best time to prune ...

I find it strange how varied the information can be sometimes, on these subjects. I live in NJ.

Online info varies because those providing that info possess varying degrees of experience and expertise. Some are great.......some don't have a clue!

Ken, I am in zone 6b, and what steps are best after a few years and the growth pattern is clear to promote upward growth vs sideways.

By nature, kousas are relatively short trees with a widely spreading canopy. Almost always wider than tall. I am not sure how much luck you will have attempting to get it to grow contrary to its natural habit.

I mean - I've seen them heavily pruned from the bottom and as a result reach higher vs some that are much wider. I'll just use my instincts. Thank you.

"what steps are best after a few years and the growth pattern is clear to promote upward growth vs sideways."

As everyone keeps telling you fighting against natural growth patterns is a losing game. If you needed a narrow tree here a Kousa might not have been the best choice.

That said- let it grow to develop some trunk girth. Over the years do some reading and educate yourself as to aesthetic pruning techniques- you can absolutely influence the future growth of most plants by carefully chosen pruning cuts. But you can't just dive in with a lopper- you need to understand how to encourage the limb grow to the left vs. the right, to grow upward instead of outward etc. - how to redirect growth.

It can be done but you need to study up.

One book I might suggest is The Pruning Book by Lee Reich.