Include Fresh Garlic in Your Diet
Garlic contains allicin, a compound that can trigger vasodilation - thereby lowering blood pressure. Garlic consumption can decrease both systolic and diastolic blood pressure by around 5-10 mmHg.
Half a clove of garlic in your daily diet is enough to realise its blood pressure-lowering-effects. Fresh is best though, as allicin is destroyed when exposed to extreme heat. It's also only produced when garlic is chewed or crushed, so if it's crushed into a dish it needs to be consumed immediately.
And garlic capsules as supplements? They're unlikely to produce much useful allicin.