CRABGRASS! Would you like some extra? ;-) I have tons of it here!

Corn gluten is the only organic pre-emergent I know of. I tried it and while the incidence of crabgrass are less where I applied it, it didn't totally eliminate it. Then again, I was a bit late in application. It should be applied when the forsythia blooms.

Yes, corn gluten is high in nitrogen (9-0-0), but it is slow release, so it should be absorbed by plants before it leaches or washes into waterways causing algae blooms. At any rate, it has to be less of an environmental detriment than chemical pre-emergents.

The war on crabgrass continues.....................

 

I've considered opening a certified crabgrass sod farm, grown with the highest quality crabgrass cultivars. It'll go right next to my grub ranch! :mrgreen:

I had figured I would be out of luck. It doesn't seem like there are a lot of options for pre-emergent or selective post-emergent herbicides in the organic world.

I agree with your assessment on the nitrogen, but unfortunately our laws put a hard limit on per-app nitrogen, regardless of source. The state even specifically addressed corn gluten meal, saying there's no exception for it. Now, I've never seen the lawn police coming around, but the law is the law.

I may just try the fertilizer rate and see what I get. Combined with diligent hand-weeding I might be able to make some progress.

 

@Deadlawn maybe chickens could be a good answer to the grub farm.
I have not tested them to see if they like crabgrass. I know they seem hard on annuals and the perennial stuff like turf bounces back well after they tear up an area. So I suspect rotating them over an area might help.

 

+1 @BobLovesGrass

Also, you get amazing chicken manure compost. ALSO, you could start a black soldier fly bin for the chickens

 

Chickens are prohibited in my town. I think the solution to all my problems is simply to move!

 

I agree with your assessment on the nitrogen, but unfortunately our laws put a hard limit on per-app nitrogen, regardless of source. The state even specifically addressed corn gluten meal, saying there's no exception for it. Now, I've never seen the lawn police coming around, but the law is the law.

I am perplexed by some of these laws. So the state would rather you use some toxic chemical than use a little extra nitrogen? And not that I am encouraging you to break the law, but would your conscience be clear if you used no other nitrogen products for a whole year while using the pre-emergent rate of corn gluten?

 

So the state would rather you use some toxic chemical than use a little extra nitrogen?

Yes, they are concerned about the nitrogen harming the Chesapeake Bay. But other than neonicotinoids, which are also banned, I can put down pretty much any other thing I want, so long as I abide by the label.

There's one county that has also prohibited any herbicide that's not listed as organic or exempt from EPA labeling. So you can't use the synthetic stuff. But the only pre-em we know of that's "organic" is corn gluten meal, which is prohibited by the state.

 

Can you not put down nitrogen at all? Or do you just have to factor it into an annual limit?

 

We're limited each year to 2.7 pounds of N per 1000 square feet, with each application limited to no more than 0.9 pounds of N/1000 sq. ft. at a time. Applications are prohibited between November 15 and March 1st.

 

@Squidgy so at the label rate, you're looking at 0.54# N/ksqft. That still gives you 2.2 lbs from other sources, which I would think is sufficient for most lawns. That adds up to another light late spring feed and a fall nitro blitz.

https://www.homedepot.com/p/Concern-25-lb-Weed-Prevention-Plus-97185/300796773?source=shoppingads&locale=en-US&mtc=Shopping-B-F_D28O-G-D28O-28_2_FERTILIZERS-MULTI-NA-Feed-PLA-NA-NA-BASE_SHP&cm_mmc=Shopping-B-F_D28O-G-D28O-28_2_FERTILIZERS-MULTI-NA-Feed-PLA-NA-NA-BASE_SHP-71700000041079887-58700004701920661-92700039807472304&gclid=CjwKCAjw5p_8BRBUEiwAPpJO67y9saXuGjM01LgIbGyHUCDoE9WwkbWyRa34TJChoBVJNoIXfjv5ZxoCx9wQAvD_BwE&gclsrc=aw.ds

 

@Squidgy so at the label rate, you're looking at 0.54# N/ksqft. That still gives you 2.2 lbs from other sources, which I would think is sufficient for most lawns. That adds up to another light late spring feed and a fall nitro blitz.

https://www.homedepot.com/p/Concern-25-lb-Weed-Prevention-Plus-97185/300796773?source=shoppingads&locale=en-US&mtc=Shopping-B-F_D28O-G-D28O-28_2_FERTILIZERS-MULTI-NA-Feed-PLA-NA-NA-BASE_SHP&cm_mmc=Shopping-B-F_D28O-G-D28O-28_2_FERTILIZERS-MULTI-NA-Feed-PLA-NA-NA-BASE_SHP-71700000041079887-58700004701920661-92700039807472304&gclid=CjwKCAjw5p_8BRBUEiwAPpJO67y9saXuGjM01LgIbGyHUCDoE9WwkbWyRa34TJChoBVJNoIXfjv5ZxoCx9wQAvD_BwE&gclsrc=aw.ds

Is the label rate you quoted the feeding rate or the weed preventive rate. The weed preventive rate is generally twice the feeding rate.

 

@always_creative I freely admit I'm not the sharpest at math, but my calculations don't match yours, based on the product info I'm seeing. I can't get the picture of the back of the bag to enlarge enough for me to read it, but the instructions PDF on the HD site says to apply 5 pounds of product per 250 square feet. So, 20 pounds per 1000. It's 8-2-4, so 20 x 8 = 160. 160/100 = 1.6 pounds actual N at label rate.

Now, the front of the bag says 25 pounds covers 1500 square feet. I don't know why the PDF and the bag disagree, but oh well. Using those figures, 25/1.5 = 16.667 pounds of product per 1000 square feet. 16.667 x 8 = 133.336. 133.336/100 = 1.3 pounds actual N at label rate.

Please correct me if I'm off somewhere.

The other problem with that product is that it's 8-2-4, and Maryland does not allow phosphorus unless you're renovating a lawn, or a soil test indicates the lawn is deficient. Yay.

 

@always_creative I freely admit I'm not the sharpest at math, but my calculations don't match yours, based on the product info I'm seeing. I can't get the picture of the back of the bag to enlarge enough for me to read it, but the instructions PDF on the HD site says to apply 5 pounds of product per 250 square feet. So, 20 pounds per 1000. It's 8-2-4, so 20 x 8 = 160. 160/100 = 1.6 pounds actual N at label rate.

Now, the front of the bag says 25 pounds covers 1500 square feet. I don't know why the PDF and the bag disagree, but oh well. Using those figures, 25/1.5 = 16.667 pounds of product per 1000 square feet. 16.667 x 8 = 133.336. 133.336/100 = 1.3 pounds actual N at label rate.

Please correct me if I'm off somewhere.

The other problem with that product is that it's 8-2-4, and Maryland does not allow phosphorus unless you're renovating a lawn, or a soil test indicates the lawn is deficient. Yay.

Not sure why that product is 8-2-4. Corn gluten only has N, nothing else. Espoma's product is 9-0-0:

https://www.espoma.com/product/weed-preventer/#toggle-id-3

Note that the feeding rate is 10 lbs/1000 sq ft and the weed preventive rate is 20 lbs/1000 sq ft. At the weed preventive rate, that is 1.8 lbs N/1000 sq ft.

 

@Squidgy and @Deadlawn I did do my math wrong, thanks for that. It is a lot of N to put down up front.

 

Wow, I can't believe that's a law. How is organic nitrogen on your lawn going to hurt anything? It isn't.

Frankly, I would just do it anyway.

 

Wow, I can't believe that's a law. How is organic nitrogen on your lawn going to hurt anything? It isn't.

Frankly, I would just do it anyway.

Nitrogen when overapplied and not taken up by plants will eventually leach into waterways. Apparently the Chesapeake Bay has some real problems with algae blooms which is why MD laws are so strict.

While it's true that even organic nitrogen can be a problem, organic sources of N are usually slow release and much less likely to leach before plants can uptake.