You want to use a bloom booster fertilizer. Vigoro is fine. The phosphate percentage (middle number in the analysis) should be 50 or higher for liquid, and 30 or higher for granular. In your case, I would use the liquid, as it will be absorbed much more quickly. Use it every 10 - 14 days. When presented with two or more options for fertilizer, choose the more expensive... price does matter.

If you have malformed buds, you may also want to check closely for pests.

For more information, every newbie should check out plumeria101.com. Michael Anders makes it all very simple.

Bob