We have a few heavyweight nutraceutical erectile dysfunction cures that are growing in popularity on the Peak Testosterone Forum. One of them is garlic with Vitamin C. Researchers have long known that Vitamin C has a postive effect on endothelial function and artery health in general - something I document in my link on Vitamin C and Erectile Dysfunction - and garlic has been known for the same. However, to be honest, neither produces particularly spectacular results on its own.
Someone, though, got the bright idea to combine the two and see what would happen. The results were nothing short of spectacular and actually met or exceeded any single drug hypertension pharmaceutical out there.  It turns out that, somehow, Vitamin C and garlic provide synergistic effects that even exceeded the power of the two summed. Look at some of the spectacular results that this study achieved on marginally hypertensive patients:
1. Increased endothelial nitric oxide by about three times baseline!
2. Dropped systolic blood pressure from an average of about 142 mm to about 115 mm at the one week point!
3. Lowered diastolic blood pressure from an average of about 92 mm to about 77 mm at the one week point!
Of course, this is going to ramp up blood flow to an incredible degree and so men with erectile dysfunction have been trying it. I know that, at least on Peak Testosterone Forum, some men have been very pleasantly surprised, especially when you consider that neither of these are expensive - quite the opposite. Look at what a couple of posterswrote:
"Hello. I'm 38 an healthy. I smoke weed and cigs. I have had problems with erections since I was 35. Some days good some days bad. Tried just about everything to help my erection. Nothing really helped. I till now I am a new man! Like I'm in my 20s! I started taking vitamin c about 2,000 to 4,000 milligrams a day. Saw a huge difference in erection! That was great! But I just found a breakthrough! Vitamin c works really well for erection, but take vitamin c with garlic an omg hard one like your 20. Rock hard. I was researching vitamin c when I stumbled upon an article. About researchers giving men in there 50s vitamin c with garlic. An it boosts nitric oxide by 300%!!! So I tried it an this us it. This is the combo that will fix you. It fixed me. I started taking both about a week ago. An I haven't been this happy for long time. It works so well that I don't think I could get this hard when I was 16!!" 
Now, if you read between the lines here, this guy likely damaged his endothelium with tobacoo and marijuana. (Inhaling the smoke from burning leaves is always hard on the lining of the arteries!) He did so much damage that he actually developed early onset erectile dysfunction at age 35. The garlic and Vitamin C actually "cured him" and brought him back to his youth.
Now does this mean it's okay to smoke? Of course not! Eventually, nothing will work for him if he continues with the smoking: it's really just a matter of time. The real point is that this nutraceutical solution is so powerful that it can often overcome, at least temporarily, the effects of a negative lifestyle.
Yet another example was one of our senior posters who has a science background. He is forever experimenting with different supplements and nutritional strategies and found that a combo of Pycnogenol, which indirectly boosts nitric oxide, and garlic dropped his prehypertensive systolic blood pressure by about 10 points from 125 to 113-116!  Again, this shows the synergies that can be achieved. ( For more information, see my link on Pycnogenol and Erectile Dysfunction.
CAUTION: If you have good erectile and endothelial dysfunction, you don't necessarily want to boost nitric oxide to supraphysiological levels. Remember that nitric oxide is a free radical and there is some study evidence that boosting nitric oxide to very high levels could cause some neurological damage.
It should be added that both Vitamin C and garlic have health superpowers in many other key areas besides simply improving erectile dysfunction. The available research shows that garlic is a potent cancer and arteriosclerosis fighter. Vitamin C is no slouch either and helps with immunity, cortisol, skin aging and inflammation just for starters. For more information, see my link on Why I Take Vitamin C.
DOSAGE: How much should you take? Well, in the above study, participants took the following:
a) 2 grams/day of Vitamin C (2 1-gram tablets of an "ester-C.")
b) 4 tablets of garlic, where each tablet contained 6 mg of allicin and 13.2 mg of alliin.
The article does not really specify how many times per day those in the study took the tabs as far as I can tell. However, generally it is better to spread out one's supplements to achieve more stable and steady plasma levels.
CAUTION: Dr. Blaylock recommends taking Vitamin C on an empty stomach, because Vitamin C can increase iron absorption. (Too much iron, which is a very common problem, is a neurotoxin and contributes to heart disease.) In addition, one study shows that Vitamin C increases nitrosamine output if there is fat in your stomach, i.e. what you ate has fat in it.
1) Nutrition Research, February 2007, 27(2):119 123, "Cellular effects of garlic supplements and antioxidant vitamins in lowering marginally high blood pressure in humans: pilot study"