Hello, Dianna. Nikko blooms on old wood. The blooms that some hydrangeas like NB have in the Fall originate from the same place as the Spring ones. They develop starting in July-August and normally should open in the Spring. But sometimes, the blooms open early. Not being as developed as the Spring blooms, they are smaller.

In the case of N/B, these blooms come at the expense of Spring blooms so I would suggest not considering the idea of enhancing them; instead get a hydrangea that reblooms like the Endless Summer Series, the Forever & Ever Series, etc.

Not pruning the stems makes them get older and stronger but if they usually originate from the ground every year then your best bet may be to put a small 1' to 1.5' tall fence around the bush. These fenbces may be visible during winter but as soon as the leaves come out, they get "lost" in the shrubbery.

Luis