You need to re-pot into a much larger container. Just make sure your existing and new container medium is watered before you transplant. That will help reduce transplant shock. Also, try not to disturb the roots or that will prolong the recovery time. Zucchini plants are very fast growing and produce a lot, so don't worry if a few flowers die off.

Thanks for the reassurance. I've never grown zucchini before and want to do it right.

Exactly as Preston' said. Zucchini are really vigorous and will become huge plants with many more blooms :-)

Josh

Repotting zucchini's is hit and miss. But starting from seed is easy. You should plant some seeds in the larger pot that you transplant the zucchini into. Every year I transplant zucchini into my garden and at the same time plant a few seeds next to them in case the transplant doesn't make it.
Every year the seeded plants overtake the transplants.
Every year I promise not to grow or buy zucchini seedlings again, as they always go to waste, but come spring I want to get a jump on the season and use transplants only to kill them when seeded zucchinis overtake them.