Eat your way to a better beard.
Copper, Zinc, Magnesium, Vitamin B, Iron, Vitamin D, and Vitamin E. These are the ingredients to hair growth.
Now, we need to preface this by saying, that there is no MAGIC cure to growing a massive manly beard. You set the stage, treat it right, and it will do what it was genetically inclined to do in the first place. The number one cause of not being able to get length is breakage. Brittle hair breaks. Period.
Copper, Zinc, and Magnesium are pretty easy to hit for your average guy - Sunflower Seeds. Eat em, you might already anyway. They're an awesome source of nutrients that help encourage hair / beard growth, and keep you from eating less pleasant things like beef liver. Spinach and Kale are also pretty legit if you're vegan or just like some leafy greens.
Vitamin B - Odds are you consume enough, it's found in meats, fish, poultry, eggs, etc. Breakfast cereals are enriched with it, and they add it to most of the Vegan Milk options. Check your carton and make sure.
Iron - Be careful with iron. Most meats are chock full of iron, and you don't need a ton in your diet as a man. Spinach, quinoa, and most leafy greens are vegetable sources, it's not hard to get what you need.
Vitamin D - Milk has been "fortified" with vitamin D for decades. Most dairy products are good sources. Realizing that your average vegan doesn't consume a lot of those things, Tofu manufacturers started fortifying with it as well. Bonus way to get Vitamin D - go outside and get some sun.
Vitamin E - Nuts and Leafy Greens, you can mix in your sunflower seeds here, spinach, almonds, potatoes, squash. Stuff that grows. Eat it.
Looking at the above list, you're pretty much on your way to eating healthier in the name of growing a better beard, take it for what it's worth, we aren't dietitians by any means, we just get asked this a lot. Some guys will try to just pop a multivitamin and take care of all of this stuff, that's not really the right way of doing it in our opinion, but you as they say "do you" A healthier diet (and any subsequent weight loss) will also cause your beard gains to increase...
What are you snackin on?