Vegetable stock

In an effort to live more sustainably and to make more things from scratch, I have begun making my own stock--usually I will make chicken stock for soup the same day and use all or most of it, but I am constantly needing vegetable stock for different soups I am making, and thought I should learn how to make stock without meat.
A friend of mine gave me the excellent idea of storing waste vegetable scraps in a container in my freezer, which I dutifully did for a little over a month. This is perfect for someone like me, because I always feel so wasteful when a bit of onion starts going wilty in my fridge and gets thrown out--scallions especially tend to get tossed when they aren't used up right away, as they have such a short shelf life. By the end of my vegetable scrap hoarding period, I had squirreled away broccoli, onion, scallions, celery, shallots, (washed) potato peelings, rosemary, zucchini, wilted salad mix, and more!
The day of, I bought a few carrots to add to the stock, and was cooking with leeks, so I added the dark green part of the leeks, and a couple of tomatoes in my fridge that were going soft. I tossed a few turkish bay leaves on top for good measure, and filled the pot with water. In general, no matter how much stock you are making, you should have enough water to cover, or in the case of floaty vegetables, mostly submerge the stock ingredients. Adding the standard mirepoix (celery, carrots, onion) is, in my book, a requirement--if you don't already have these items on hand, you'll want to pick them up before making your stock.
In addition to these things, you can add wine to the stock, though I did not in this case. Generally, with stock, you want to just cook it for a long time to really ensure that the flavor (and nutrients!) are thorough. I brought the pot to a simmer, and let it cook away on medium heat for a little less than 2 hours covered, then uncovered and reduced for about an hour and a half. The stock that I ended up with was a lovely light brown color, and tasted great! I got about 6 cups of stock from my recipe, and put it in the freezer in 2-cup portions.
Depending on what you'd like to use the stock for, you could put any number of things into your stock. You might want to add more herbs, use fresh ginger, tons of garlic, add colorful beets or beet greens for a brightly colored stock... you name it. I look forward to more stock experiments in the future!