I'm in my thirties and I've had borderline what is classified as high for a long long time, which was about 135/85. My father has high blood pressure and does as many natural things as possible as well as medicine. Well I take my blood pressure daily if not a few times a day to see if some vitamin/herb is really helping me and what isn't helping me. I can tell you that hibicious tea helped me a lot, but I honestly stopped drinking it. The reason I stopped drinking it was because my blood pressure for months was consistently 117/63 give or take. I think for months I never saw anything higher than 119/69 and I couldn't figure out what I changed to help my blood pressure drop and stay dropped.
Well I make a shake every morning and I've been doing this for a long long time. I ran out of hemp protein power, so I started making eggs. My blood pressure went up day after day that week up to about 132/85. I don't know what is in my protein shake, but it's the only thing that I changed. My shake has hemp protein, bannanas, cocoa powder, chia seeds, yogurt or kefir milk and blueberries. I'm guessing it's the hemp protein that is making the difference, because when I was using whey protein my blood pressure was the same. I'm getting so much more fiber when I take my shakes, which if you google high fiber and blood pressure you'll see studies that high fiber has been shown to lower blood pressure. I think the yogurt/kefir and cocoa powder might help as well, but you would think it would be out of my system after a certain time? When I take my shake in the morning it doesn't matter what time I take my blood pressure it's low.
I agree with jfh that I try to keep my blood pressure around or lower than 120s/80s and anything higher I try to make changes so that it's lower. Any study or anything that comes out I'd try personally if it's natural. cq10 had a slight difference in my blood pressure, but hibiscus tea I think was the most impressive. I just didn't like drinking it that often as I already drink other green/oolong/rooibos and wine very often.