Another one to look at is pomegranate. A friend of mine was having side effects with his BP medicine, and I made the suggestion to try it, LEF brand pills or POM juice. He was able to get off, had same BP as when on meds, without side effects. There are lots of studies to look at on this on at pubmed, essentially a beta-blocker with some other actions.
Lastly, most people are deficient in potassium. Get some potassium glutamate powder to supplement (not pills as they are regulated to be under 100mg). RDA is 5g, and most people are under 2g a day intake. I have taken 500mg worth of potassium, daily in water, for years without issue.
If I was looking for supplements for BP, based on research, I would go with pomegranate or potassium.