Agree with GG for the most part. That recipe will not do what you want without killing other grasses.

Check out this video on YouTube. It documents the use of baking soda to kill crabgrass and dallisgrass in St Augustine lawns. It is from 10 years ago when the research came out in Florida. Quickly there was a product on the market where baking soda was listed as the active ingredient. At $14 per pound that seemed a little high to me. About a year later the product changed and cinnamon was listed as the active ingredient and baking soda is listed as the inactive ingredient. I think the cinnamon is a smoke screen to keep people from knowing how simple it is. The video shows it pretty well.

I have used baking soda successfully. The only trick is to make the water stick to the crabgrass blades and not ball up and roll off like it does normally. That is done by spraying the crabgrass first with a soapy solution or with diluted molasses. Both make a good sticker.

Since you are in zone 5, you likely don't have St Augustine. If you try the baking soda approach, use care to keep the soda dust on the crabgrass and not get any on the real grass. Also, use care not to inhale the baking soda dust or get ANY into your eyes. You'll know immediately if you do either. If it's in your eyes, flush with water. It is the opposite of pouring acid into your eyes, but the pain is about the same. Ask me how I know ;-)

I dunno, that sounds...anecdotal to say the least.

" Homemade remedies are seldom very effective in their application, otherwise someone would have taken the recipe and patented it years ago."

Sigh. Homemade remedies vary in their effectiveness and, as with the soap and kelp we use around here, can be very, very effective. Companies certainly do offer the same thing and cover the much greater expense with pretty language, attractive labels with four-color printing, and expensive advertising. That does not necessarily imply the product is better, "patented" or not. But they certainly charge more because they're not offering their expertise for free.

This particular formula? It actually does have a use and a sales niche. It's called "horticultural vinegar," which does work. In some cases. With proper care.

Would it work on crabgrass? On some weeds, if young enough, done on a hot day, in full sun. Don't get it in your eye because corneal burns aren't fun. So wear goggles. Wash your hands before you remove said goggles. Twice. With soap.

It's a decidedly niche product and one I don't, personally, use for just that reason.

And I wouldn't bother with the salt. I'm not a hundred percent sure about the baking soda, either...if you do something with vinegar and/or sodium bicarb, leave enough time to make sure you can go back and re-treat with an herbicide. A good rainfall will interfere with either.

What's the long-term impact? Not that bad, really. Soil toxicity is low unless you're really dumping it on and even then, it can be flushed out. I'd be just as worried about the acidity (which will dispel the soil calcium) as I would be about the sodium...if you were dumping it by the barrel-full.

A gallon or so sprayed across your property? No biggie, sodium levels are not much greater than if you had used soap across your property.

With the baking soda, it's the other way around; you're increasing alkalinity AND adding sodium. There it's more, but you'd have to measure the weight. I doubt it's going to be enough to be an issue, but make sure. A few cups per thousand square feet scattered? No problem. Ten pounds? Um...that's a lot of sodium.

For the reseeding process, if you're working with areas that are crabgrass and nothing else, I'd recommend wiping the area clean with Round Up. Kill it all. Nuke it from orbit, it's the only way to be sure...

For areas with St. Aug (or whatever grass you do have if David is correct), use whatever method makes you happy. But as I noted, leave enough time to go back with a grass-compatible herbicide if you must...

" This particular formula? It actually does have a use and a sales niche. It's called "horticultural vinegar," which does work. In some cases."

Sigh......No, that formula is NOT horticultural vinegar. Horticultural vinegar is a specific concentraton of acetic acid....far above what one finds with table vinegar. Table vinegar is typically a 4-5% solution of acetic acid, sometimes as much as 7%, depending on the source. Horticultural vinegar is a 20-30% solution. It also contains no other ingredients other than a surfactant, often yucca extract - no table salt, no dish soap. And is not always easily available in that concentration and can be dangerous to use. In concentrations over 11%, acetic acid can can burn skin and casue eye damage, and concentrations of 20% and above are corrosive to tin, aluminum, iron, and concrete and can even cause blindness. Such herbicides should be applied while wearing goggles and protective clothing.

I think 20% vinegar is always dangerous to use. I was on a field trip at a military base once (anecdote coming) about 45 years ago. Someone grabbed the hort vinegar instead of the household vinegar to strip wax off the floors. They had to evacuate the building. Breathing was painful. If that happened today we'd have all gone to a hospital for observation.

With dense St Augustine, crabgrass is almost never a wide spread problem. It is a spot problem as shown in the video, and is easily taken care of. I have to say it is awesome to see crabgrass turn black in a day or two.

I think I found the source of this original post. Silver Cymbal is a YouTube lawn guy. He posted this video on July 25. He also cautions against using it on the lawn because it is non selective. I still believe it only kills top growth, but if you're using it in flower beds, that should be fine. Just reapply as necessary. I also don't like using 20% (30%) vinegar.