Weed killer update - request for ideas

The vinegar + salt + soap weedkiller that was so enthusiastically talked about online was a total bust for the weeds I was trying to kill. The thistles merely laughed, and I suspect the vinegar made them tougher. The broadleaf grasses browned, a little bit, and then continued to grow. We knocked down the broad leafs in the tiller activity over the weekend, but I know they'll come up just as fast and just as strong.

I am more than willing to suggest that operator error had something to do with this failure. Did we wait too long and the weeds were simply too large and established? Did I not spray enough? Did the dew on the grass affect the strength of the vinegar? Was there not enough sun? There are simply too many variables to identify the problem, but I still have a lot of grass and thistles to deal with.

I am convening a meeting of our garden leadership this week to talk about our options. One of our gardeners is working on some solutions, but I've just about had it with the thistles in our paths. We have sheet mulched and wood chipped our paths for three years, and the thistles just keep on coming. We have spent hours and hours manually digging them in both spring and autumn and the turned up soil just seems to yield more thistles.

I have threatened, jokingly, but now I'm starting to get more serious, of hitting the paths with a one-time application of RoundUp.  This  is specifically and strictly forbidden by our garden bylaws; we are an organic garden. But I simply don't know what else to do.

Does anyone have any suggestions?

Vinegar + salt + soap = an organic weed killer?

In our community garden, we have a weed problem. Actually, we have three of them, and each is 130 feet long and five feet wide. These were our community vine patch that over a two years has produced many many pumpkins, squash and cucumbers. But interest in it has waned as the squash beetles destroyed many plants.

So this year we are converting the three long beds to perennials; asparagus and black berries. We may rethink the wisdom of the latter, but for now, it seems better than fighting those squash beetles.

The long rows where we'll plant our new perennial crops are a weedy mess.

Our community garden is organic, so no Roundup. I found a recipe online for a gallon of vinegar, a half cup of salt and a tablespoon of dish detergent to kill weeds.  My first reaction was if this really worked, everyone would be using it.

Then I thought that Monsanto sells Roundup, not vinegar, so maybe it does work but doesn't get much press.

At the grocery store, I found a special "cleaning" strength vinegar, 6 percent vs. 5. Most recipes said the 5 percent would work, but what the heck, for a buck more a gallon, I bought the stronger stuff.

The recipe says that the vinegar solution needs to be put on plants on a sunny day, because it's the vinegar + sun that fries the leaves.

In addition to hitting the grassy beds, I also spot treated thistles coming through our paths. My theory: hit them when they are young, and hit them several times, and maybe we can kill them.

I did this on Saturday morning, and haven't been back out there to see what happened. I'll let you know...