We first tried buying locally in the Grand Forks plant and garden centers, but to no avail. In fact one worker at one of the centers suggested that we look into having a professional company come an spray our lawn (the direct opposite of what we wanted).
So then I turned to on-line research. With a lot of digging, the one product that seemed the most natural and chemical free was Iron X®. It isn't necessarily cheap, but it is something that can be diluted so that makes it more cost effective. I bought a bottle of it to try and to be honest, my first application wasn't too impressive in terms of weed death. I tried again a few weeks later, adding in some liquid dish soap (on John's recommendation) so that it would stick better to the weeds. And I really think that helped the process.
Here are a few pictures of our dead weeds.
It's a little hard to see since our grass is so dry due to the summer drought, but the dandelions are the black things. They really do turn black and crispy within a day of application. And for some reason, I get a big kick out of seeing my weeds wither and die. After this successful experiment, we bought another four bottles since we have a large yard and nearly as large weed infestation. I know that weed control will take a few years, but now that I have a product that appears to work, I can hit the weeds hard early in the spring, as well as later this fall. And add in some more grass seeding, to help fill in the patches, I'm hoping that our yard will be naturally weed free in a few years. Stay tuned for progress updates!
As a disclaimer, the one bummer is that my less than accurate spraying did hit our fence and since the concentrate is a dark brown color, it stained our fence. I am optimistic though that this will fade with time, and with some rain and snow hitting it.