Hello!

My experience with dogwoods is pretty limited, so I sadly cannot recommend fertilizer techniques. What I have noticed though is that, at least in the wild, Red-osier really likes to have full sun, and Round leaf (yellow twig) likes more filtered shade since it is somewhat more susceptible to sun scald. The part of Minnesota that these trees are native to, namely the arrowhead, is often dominated by large red and white pines, and these are the arrowhead where dogwoods see the most success.

Just as a general gardening rule, trees that are excessively lanky are often starving for sunlight. If you can provide a picture or two, I could hopefully be a bit more helpful with a diagnosis.

I applaud you for choosing to plant dogwoods. This often-overlooked genus has a very high wildlife value in the winter and can often be quite beautiful.