Use of Baking Soda

Use of Baking Soda

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stumped – posted 02 October 2003 07:29

I sure hope someone can help me with my problem.

I live in Orlando, Florida (Zone 9A/9B) and either have Floritam or St. Augustine. I utilize the Scotts Fertilizer Products, however I am constantly battling crabgrass.

I have heard using baking soda will kill crabgrass, however I am afraid this will kill my ‘real’ grass. I would prefer to use a natural deterrent.

Any thoughts?

Thanks in advance!


ted – posted 03 October 2003 13:02

i would wonder why you’re having “crabgrass” problems with the st. augustine- it’s usually so thick nothing can get in. you might want to make sure you’re using quality fertilizers at the right time of year and water/mowing correctly. i can’t imagine a situation where crabgrass would be a problem ( provided that it’s truly crabgrass). as far as the scott’s products go, there’s nothing particulary magical with them, they’re definitely not the best products on the market, and as for the baking soda- just forget it. i believe atrazine would be your product for the crabgrass, but i would probably defer to florida turf folks on this one-

bpteos – posted 08 October 2003 14:16

I also live in Orlando, Florida. I have used the baking soda to kill crabgrass. It usually takes only about a day to see results. It dosen’t seem to harm the other grass. I have several varities of St. Agustine (Floratam, Delmar, Palmetto)

rkm1003 – posted 08 October 2003 15:03

quote:Originally posted by bpteos:I also live in Orlando, Florida. I have used the baking soda to kill crabgrass. It usually takes only about a day to see results. It dosen’t seem to harm the other grass. I have several varities of St. Agustine (Floratam, Delmar, Palmetto)

HOw did you apply it??????/

rgjack – posted 09 October 2003 13:09

quote:Originally posted by ted:… as far as the scott’s products go, there’s nothing particulary magical with them, they’re definitely not the best products on the market …[/B]

Ted, please, what products do you consider superior to the Scotts products? …and reason for same? THX

Dchall_San_Antonio – posted 09 October 2003 21:39

Florida seems to be the home of the idea to use baking soda against crabgrass without doing harm to other grasses. The suggestion for applying it is to put some in an old sock and whack the sock onto damp crabgrass to dust it on. The weed turns black in a few days. After that I’ve heard mixed results with the South having better luck with the approach.

Baking soda is an antifungal agent so I’m wondering if there is some fungus that crabgrass relies on to live???

seed – posted 11 October 2003 20:58

When I tried it, the baking soda turned the crabgrass leaves black and shriveled within 24 hours. The rapid results suggested some kind of sudden shock, maybe osmotic. Unlike salt or something granular, the baking soda sticks to the leaves, especially crabgrass because is minutely hairy.

I had just sprinkled the baking soda out the box, pretty much just on the crab grass. I didn’t notice any injury to the St. Augustinegrass, but I might have just been sufficiently selective that I didn’t get much on the St. Augustine.


ted – posted 12 October 2003 13:51

any of the “hardware store” consumer type products are not going to be as effective as pro products, and the advice you get is even worse! try calling a local Lesco Service Center in your area and purchasing the products there. You don’t have to be a licensed applicator to purchase most of their products. The Scotts guys actually make a line of golf products which are very good, but you’re not going to be finding them in your local hardstore. And no, I don’t work for Lesco.

seed – posted 13 October 2003 15:25

The one pro product that worked was Asulox which is no longer available with a residential turf label (now only for ag). No other selective postemergence herbicide has been developed that controls mature crabgrass in St. Augustinegrass. Prograss is effective against seedling crabgrass. MSMA kills crabgrass, but at the rates required it is highly damaging to St. Augustinegrass. There are some sedge herbicides that have crossover effects on some grass weeds, but they will not remove crabgrass. I was quite skeptical of the baking soda idea, and I don’t know how much harm it does to St. Augustinegrass, but in my one experience using baking soda on crabgrass, it was completely defoliated, which was amazing. If there were a “pro” product that works, I don’t know what it is.


Sharris – posted 22 October 2005 07:09

Ted – not sure if you’re from FL or not but crabgrass has always been a problem with St Augustine grass – as well as other weeds. St Augustine is not invinceable. There used to be chemicals on the market to kill it – but they’re not available anymore due to restricions on harmful chemicals to our environment. Atrazine will do nothing to crabgrass – as a matter of fact it seems to like it and thrives even more. I’ve used baking soda on crabgrass – it works better than anything else I’ve seen available and it doesn’t harm St Augustine. You don’t want to pull the Crabgrass because all you’re doing is spreading seeds and which will make it worse. I agree with you on the Scott’s products – they are primarily designed for northern grasses. Lesco is a local Florida company that makes fertizers specifically suited for FL climate and soils. The best recipe I’ve found for keeping St Augustine healthy is to use a pre-emerant in the spring and fall such as Halts Crabgrass Preventer (this does not kill Crabgrass – just merely keeps if and other weeds from germinating), then use a sedge product such as Image – spring and fall – this kills most weeds but not Crabgrass or a few others – do not use Image in the hot months – it stresses the St Augustine which is why you want to use it in the cooler months. It works quite well. It will temporarily stunt the growth of the St Augustine – but it will come back – if you don’t want weeds – this is the way to go. Fertilize every 6 to 8 weeks – I prefer Lesco. You need to do it every 6 – 8 weeks mainly during the warmer months because our soil here in FL is mostly sand and we get a lot of rain. Hope this helps.

wdstamper – posted 23 October 2005 19:26

I also live in Florida and Crabgrass is a real problem. My front yard is about a half acre and used to be solid St. Augustine until this year. Crabgrass has taken over just about everywhere there is no shade. Does anyone out there know if I can spray baking soda from a hose sprayer to kill the Crabgrass and start taking back my yard? If so, how much should I apply and how many times should I apply it to kill the Crabgrass? Any help would be appreciated.

orlando – posted 03 November 2005 10:07

To Ted – Crabgrass can kick St. Augustine’s butt at times! It handles the heat and water schedule much better than St. Augustine in the peak of summer.

I’m also in Orlando and two types of crabgrass have invaded a portion of my lawn. I’m using baking soda (sodium bicarbonate or sodium hydrogen carbonate) with great early results. As stated before, the crabgrass turns black as quickly as half a day later. It is great. I’ve fought this crabgrass by hand, Scott’s preventer, atrazine, resodding for so long … none of that works except the manual labor and the manual labor is an ongoing neverending painful battle.

I just sprinkled it directly from the large $2 box I bought at Publix. I lay it on pretty thick. St. Augustine and an unwanted patch of bermuda both appear to be resistant to it. I’ve seen one other weed I’m not sure of die from it too. A large box might be good for 400 square feet the way I was spreading it. I’m on box #3.

If St. Augustine has a delayed negative reaction I’ll post it here but my test patches are holding up …

orlando – posted 04 November 2005 09:06


This is after 3-4 days but I started pulling up the crabgrass, mostly due to the ugly black mixed in my green lawn. Some things I noticed:

Blanket crabgrass:

Cerberus – posted 16 November 2005 11:27

“Does anyone out there know if I can spray baking soda from a hose sprayer to kill the Crabgrass and start taking back my yard? If so, how much should I apply and how many times should I apply it to kill the Crabgrass? Any help would be appreciated.”

I tried mixing a small box of baking soda in 2 gallons of water and applying it with a backpack sprayer. It had no visible effect on the crabgrass. The solution just ran off the blades. Maybe adding a surfactant or spreader/sticker would improve results.

I will try the dry application method today.

weedsrus – posted 19 November 2005 09:43

I live in Orlando and have tried baking soda on multiple times. I tried putting it on really heavy and it had no effect. Then one day I had some baking soda on the grass and a piece of PVC laying on top of the grass. The weeds under the PVC were the only ones affected by the baking soda. Why is this cried weed man? Then it hit me, the condensation was key!

The key to baking soda seems to be: wet the grass then apply a light coat of baking soda. It seems to work on the grass leaf. It doesn’t do any good if you put it on really heavy if it doesn’t stay on the leaf. I would think that putting it in the hose-end sprayer might do some good given my theory but I haven’t tried it. My next task is to quantify the amount of baking soda needed. Good luck to all you soldiers in the fight against weeds. “May the soda be with you !”coon123@pol.net

BuckinNC – posted 20 November 2005 09:08

Astute observation. If you come up with a flowable solution I’d like to learn of it.

turftajar – posted 30 November 2005 13:33

I have overlapping areas of St Augustine and centipede with the crabgrass. Has anyone tested the effects of the soda on centipede?

rpeebs – posted 07 December 2005 07:46

Hey Orlando – any new updates? Sounds like you’ve got it on the run. I’m looking for the solution and I wan to try your technique if it worked.

BW – posted 31 December 2005 12:06

I’m in Melboure, FL. Does it make a difference what time of year the Baking Soda is put down. If I put it down now (January) will it weaken the St Augustine, ot is it better to wait for the growing season?

JRRTolkien – posted 18 January 2006 05:32

I also live in Orlando. You can go to BJ’s and buy baking soda in 12lb bags for around $5 a bag. I actually just put it in my broadcast spreader and covered our lot (approximately 2000 sq. ft.) with 3 bags. As in the other posts, the crabgrass turns black, but the baking soda doesn’t harm the St. Augustine. I plan on following this up by putting down a pre-emergent crabgrass killer.

none – posted 07 February 2006 12:19

Try this it has worked for me.Mix a pound of baking soda with a cup of Arm&Hammer laundry soap(powder) in two gal. water and use sprayer.

Bob – posted 11 February 2006 21:16

JRR…How does your lawn look now…any update?

Chubber – posted 13 February 2006 15:45

I can go +1 on the baking soda. My neighbor showed me the trick. A 5 lb box seems to do about 100 square feet for me. The real secret is to apply it when the grass is damp (I use plain water in a sprayer before application if there has been no rain) so it kind of cakes onto the leaves. 1 day later they are turning brown and a week later they are black and just about dead.

Of course, if it is thick, then you will want to plug in some more grass plugs if there aren’t any grass rhizomes left.

Alex_in_FL – posted 25 February 2006 07:52

The easiest solution is to put down a good pre-emergent and avoid the crabgrass all together. I am putting out my pre-emergent this afternoon (and making my 2nd flea spray application).

Zamog – posted 22 March 2006 11:42

I used it on my lawn and worked great! Now all the little boys in the neighborhood come to play in my yard!

crabgrasser – posted 02 April 2006 10:46

I live in SC and have a beautiful lawn of crabgrass with a little bit of bermuda patches. crabgrasser – posted 02 April 2006 12:01

In the first picture I posted above how the grass is brown around the plants? Did I kill my grass?

Ahhhh crap, tell me I didn’t kill my grass.

Free Man – posted 22 May 2010 09:08

So does this baking soda trick kill more weeds than just carpet grasses?

And also, has anyone used baking soda in Zoysia grass, which I have? Does it harm it?

d.k – posted 02 June 2010 09:22

I tried a liquid application to the crabgrass sprouting up in the seams of the front sidewalk,

Used a hot pot to boil some water, poured it over the baking soda and stirred it todissolve as much as possible, then let itcool, and added some detergent as a sticker. Put it in a hand-sprayer to hit theweeds on the walk.

Didn’t seem to make much of a dent in liquid form that I noticed. I will try it straight from the box tomorrow after general watering.

barefootinthesun – posted 26 October 2011 09:49

Yes, it works! Such a shame that the lawn services can’t use it because it is not ‘approved.’ So, mix with some cinnamon so you can see where you are distributing it. Apply when the dew is still on the grass. Don’t go crazy, a little goes a long way and over application can change the soil’s PH as well as kill the St. Augustine. You will see results in as little as two hours. I had a 10 x 20 area to treat and eliminated the crabgrass in two applications. I don’t know of any way to get rid of the Torpedo grass other than digging it out. You will have to go down at least a foot to get the runners. If this is not an option you will have to use Roundup or something similar. The good news is that the St Augustine will fill it back in within a few months. If you are impatient, get plugs. Don’t forget to add a little started fertilizer to each hole! Good luck!

Kayu – posted 19 December 2011 17:02

The baking soda method is a new one for me, one I am looking forward to trying next year. I have a mixed St. Augustine/Centipede lawn in Atlanta that I have labored over and lovingly applied Ringer Lawn Restore (best “natural” fertilizer ever) and Image for St. Augustine and Centipede twice a year (hate using poisons but what do I do?). Ringer is wonderful stuff (can get it delivered for free to your nearest affiliated hardware store by going to dottiest.com) and the Image keeps my lawn mostly free of weeds except for crab grass, which kicked my but last year. The good news is that the crab grass is concentrated in limited areas but it is spreading.) Then to top if off I had a chinch bug infestation late summer which killed one small section of my lawn and a weakened a large swath in back. Well, I have the winter to plan and will post photos next summer.

seed – posted 27 December 2011 02:49

Thanks, Spriteman, for sharing a good and informative experience. Please let us know how the sodium bicarbonate (baking powder) works after the second application.

Just two caveats. Surflan (active ingredient oryzalin) is a preemergence herbicide so I don’t expect it would do anything for chinch bugs.

And separately at the end you mention preemergence herbicide in connection with crabgrass. Ideally in Lakeland in most years you will experience frost, to temporarily eliminate most of the crabgrass, and thus give justification for using preemegence herbicides to keep it from coming back, sodium bicarbonate or not. In south Florida, we generally don’t get serious frost so we are stuck with home remedies such as baking soda.

Spriteman – posted 27 December 2011 02:49

Greeting and salutations from Lakeland, FL to all of my fellow weed ninjas.

I started a weed treatment attack in early summer of 2011. Here are my results utilizing baking soda/bicarbonate. I have an approximately 3000 sf lawn. About 400 sf of that was very nice mature St. Aug/Floratam. – didn’t mess with it.

The rest of the lawn is a cornucopia of weeds – mostly southern crabgrass. I had an area about 15 x 30 near the front door to the house that I mapped out as a test area where I would test different weed control methods.

I was late getting started on treatment for 2011 and applied Scotts Weed & Feed – aka Atrazine. Over the next couple of weeks the few runners of St.Aug left in the yard seemed to perk up and a few of the weed types started to show signs of stress. After 5-6 weeks I noticed that most of the weeds were growing again and like others who have posted earlier noticed that the crabgrass seemed to benefit from the fertilizer. So, I decided that wasn’t going to work.

I paid a visit to my local lawn & garden store here in Lakeland (plug Peterson’s Nursery) and shared with them my plight. They suggested several courses of action that would bring the weeds under control. They gave me a nice one page 2-sided StAug yearly calendar of treatment schedule.

The three main points from it are: 1 – supply nutrients for the grass, 2 – kill weeds, and 3 – kill bugs. All of the other actions help but are not critical in my book. I am using the schedule as a guide since we all have different situations with location and weed issues. I will perform all of the actions listed I just believe that you need to adjust the frequency of the applications for sun/temp/rain/etc…

1st – the fertilizer that I was using was okay – the main use for it in my book now is to supply nutrients not kill weeds.

2nd – kill weeds – the new deal here is the bicarbonate – more on this later.

3rd – use of a good pesticide to kill chinch bugs and mole crickets. If you see a brown spot forming in your nice StAug – hit it quick with powder mix that you put in a hose sprayer – Orthene. You don’t even have to cover the entire lawn if you don’t want to – just don’t let them expand the brown spot. In a few weeks you will see your lawn return to it’s normal green hue. The quicker you treat the bugs the less damage you will get.

Okay – let’s say that you’re existing StAug is growing nicely and there are no signs of any pesky bugs.

So, let’s focus on weed destruction. The earlier posts hit on the topic but I will lay it out like my Peterson folks told me.

First, I like to have a fresh cut to begin my bicarb treatment. Now this is just my reasoning but it seems to me that the longer that the bicarb is on the weed leaf the more thoroughly it will kill it. Also, and this is BIG, the crabgrass has to be growing again after the mowing.

I didn’t really understand that at first and I just mowed the weed areas and right after misted up the area and sifted the bicarb onto the weeds. I did see some damage to the weeds but it wasn’t very long afterwards that the weeds were returning.

So, after that first test I remembered what they had said about putting the bicarb down while the weed was growing. So, the next test was a good mow, then allow the weeds a couple of days to begin growing again and on the third day I again misted the weeds and sifted the bicarb onto the weed leaf again.

I put it on fairly heavy. Let’s just say that you could see a good white dusting on all of the weed areas when I was done.

THAT DID THE TRICK – within two days ALL weeds were showing distress and within 4 or 5 weeks the weed areas were bare.

One problem that I created was I probably was not discriminating enough when I was putting down the bicarb – I should have tried to apply it a little more sparingly when right on the existing StAug. Another treatment later in a different area proved this to be correct.

But here’s the lucky coincidence – by over applying I did hurt the existing StAug, however, I definitely killed all of the weeds – ALL OF THEM. The StAug was hurt but I watered it well over the next couple of months and surprisingly the StAug recovered. And here’s the real kicker – almost no weeds grew in the bicarb treated area. It took almost 6 months for the 1st weeds to return to the treated area. I think that the bicarb – if applied heavily, alters the soil chemistry and won’t allow the weeds to germinate.

Since that time the StAug has been growing like crazy and even without adding plugs or sod is filling the area in via runners growing straight out and then creating more runners from the nodes growing perpendicular from the original runners. I estimate that by the end of Spring 2012 the area will be filled in completely.

Fast-forward to 12/2011 – I just applied bicarb to the rest of my weed infested lawn. Within two weeks it has already knocked down just about every weed in the covered area. I will let the bicarb continue to work and will probably hit any areas where I might have missed and once I feel that all of the weeds are gone.

Once I feel that the soil is okay for plugging I am going to plug the area about 18 inches apart. I would just sod the area but I’m trying to save a buck or two in the process.

After the plugs have had a chance to get established I will spot treat with the bicarb. The folks at Peterson’s said that they go out with a water bottle sprayer and a sifter of bicarb and get after those evil weeds.

I plan on hitting the lawn with fertilizer about every 8 weeks this year. It seems like with all of the rain we’ve been getting it is gone in about that amount of time. I’m hoping that the following year – the StAug will be so full and healthy that I can dial all of the chemicals back and allow the grass to fend for itself.

Well – that’s my two cents – hope this helps in some way – post back if you use any of this and it works/doesn’t work.


1 – If you apply the bicarb on a windy day and you think some of it might have gotten on a good StAug area – just give it a quick mist off with water and it should limit any damage.

2 – Take an old plastic coffee container and punch holes in the top all over like a salt shaker and you can use this as your sifter.

3 – You can buy 50lb bags of bicarb at your local feed store – you’ll pay about $25 – but if you try to buy it somewhere else it will probably be double that. Farmers use it for their livestock in some way – I am sure someone out there knows why.

4 – Apply dolomite (aka Limestone) twice a year – this will keep the soil in a good pH range for StAug.

5 – Make sure you lay down a good crabgrass pre-emergent (Surflan) at the proper time for your geography. In Lakeland I’ve been told that’s right at Feb 15. Timing is everything.

6 – Don’t put down new sod when the temp is over 90F – it will most likely burn it.

[This message has been edited by Spriteman (edited 27 December 2011).]

bwach – posted 03 March 2012 00:39

Aparently it’s the pH levels in the baking soda that kills the crabgrass and spares the st augustine. I tried this last year on some patches in my yard and had no luck after watering the powder in. Came to realize that by watering it in i was actually neutralizing the powder. Put it on dry and lightly mist if it’s windy. Recommend waiting for a calm day and just leaving it dry. Also, I like to flip the weedwhacker over and grind the crabgrass down to roots and then sprinkle the baking soda. Yeah, you see some ugly dirt spots, but I think it’s better than black crabgrass spots. Ensure you use a good preemergent to keep more spots from springing up.

OrlandoYardMan – posted 11 September 2015 07:58

Thanks for the awesome advice about using baking soda for treating crabgrass in St Augustine.

My question is, what do you do after the crabgrass dies? Pull it out and replug/resod the area or just leave it be and let the good grass grow back?

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