Joyce....think about it. If pH is altered so much that the soil is unfit for grasses and weeds, which are notoriously sturdy......don't you think that desirable plants would be affected?

Baking Soda, Sodium Bicarbonate, is an alkaline substance with a pH of abnout 8.2. Baking Soda will not lower a soils pH. You would need pounds of Baking Soda to make any significant change to a soils pH.
As a general rule of thumb what is available to organic gardeners to lower a soils pH is sulfur, but how much to use depends on what your soils pH is, how much that pH might need to be lowered, the type of soil you have, how much organic matter is in that soil.
If your soil needs a pH adjustment the best source of information about doing that would be your state universities Cooperative Extension Service. They will be able to tell you what your soils pH is, after a soil test, and what and how much material is needed to lower that pH. As a general rule of thumb it takes about 1 pound of sulfur per one hundred squaer feet of garden to lower the ph 1 point.

Pinterest strikes again! I've see that "tip" all over that site, and it is not true, does not work.

If it could alter pH enough to suppress weed growth, there is nothing to keep it from dissolving when you water it and spreading into the flowerbeds and killing them too.

Here is a link that might be useful: Sodium Bicarbonate

Thanks for all the replies and "yes" I did see it on Pinterest!

Sodium in clay soils, not this boy, ever! Not sodium bicarb., sodium chloride, not sodium anything. Sodium causes clay soils to disperse, that is your pore apace and associated soil structure will be destroyed and along with it you can expect poor drainage and root rots from no oxygen in the soil. The goal is to improve soil structure by doing things like adding O.M. to it. Ok, I'm off my soapbox now, anybody else?

If you are just trying to control a few weeds/grass/sedge from coming up into your garden I suggest two different methods. #1 pull them......yeah I know labor intensive but it also is a good way to identify what's a keeper and what's not. #2 horticultural vinegar (20%acidity) or just reg white vinegar (norm only 5% acidity) and put on a spray bottle top. Sprench the leaves of the weeds when the weather is above 75degrees in full sun, You can hear the cell walls crackle! This won't change the ph of your soil but will kill the weeds. Some weeds need a few applications!! Then cover your garden bed with a mulch you have handy to stop further weeds. I like a very light sprinkling of dry grass clippings (cuz I got um). Good Luck!

I have a patch of soil with a pH of 9, due to the previous owner dumping wood ashes indiscriminately all over the places. No vegetable crop grows there but weeds are growing fine.

I used baking soda mix for my petunia as a fungicide, it worked well... same goes to my grapes, less stress for them and are growing just fine and well... didn't use it to kill weeds, as weeds are sprouting around the plants where I placed baking soda.

I've read you can use baking soda and water for powderly mildew and it did seem to help when I tried it a few years back on my roses. WIll it work for other fungal problems too? We've had a lot of rain lately and I worry my basil might get fusarium wilt I think its called. Every year my basil starts out great but gets brown leaves and it deteriorates rapidly. I believe I read that is fusarium wilt and is common is sweet basil.

Baking Soda, Sodium Bicarbonate, mixed 1 teaspoon per quart of water (3 tablespoons per gallon) has been used as a control for Powdery Mildew for many years to control Powdery Mildew, Black Spot on Roses, and several other fungal diseases. Some have found that adding a teaspoon of an oil makes the solution more effective. Others report that the same mix of Potassium Bicarbonate is more effective, but I do not find it as readily as Baking Soda.

kimmq is kimmsr