An appealing method for dealing with invasive plants

Joel_BC

Super Self-Sufficient
Joined
Nov 21, 2011
Messages
1,284
Reaction score
318
Points
227
Location
Western Canada
Here in my area we have some frustratingly invasive plants. For instance, on our place we have knapweed, which is a tough plant that grows large, vigorous, and tough-rooted once it finds an opportunity, and which produces many seeds each year. (Maybe I’m late to learn about this method, so forgive me if this seems old-hat.)

Someone wrote in to a local letter-to-the-editor column about this approach to fighting such plants: use agricultural urea (46-0-0) right at the base of each plant. As most here will know, urea is a naturally occurring chemical that is found in urine, and also in a lesser concentration in our blood and lymph. Ag urea is usually sold as powder or micro-pellets.

I’m an organic grower. Why would this “chemical” approach appeal to me? Well, knapweed invades & thrives in dryish areas with “unimproved” soil. We have some of that because our water supply is limited, and there’s some cleared land on our place and the adjacent properties where knapweed has been taking hold. I’ve tried dealing with the plants by weed-whacking them when they appear early in their season (to avoid the seed-formation phase), and by digging them out. Digging up the roots can require 15 minutes per plant, and it’s aggravating because you can’t spare the time and you know you’ll be doing it again next year!
:barnie

Knapweed is a plant that cannot utilize much nitrogen, therefore it dies after the urea application. The article I read says hawkweed, comfrey, and dock are among the pants that will be affected similarly. Over time, soil bacterial will digest urea, as it is a natural molecule.

BTW, this is very different than broad application of artificial nitrogen fertilizer to a field — which is controversial due to possible undesirable influence on the water table below the fields. In many places, ag urea can be bought in either hefty sacks or small quanitites (by the pound).
 
Last edited:

baymule

Sustainability Master
Joined
Nov 13, 2010
Messages
10,701
Reaction score
18,597
Points
413
Location
East Texas
I like that. I am as organic as I can be. I have chemical sensitivities to the point that I can't walk down the soap aisle at the grocery store. No cleaning products either, I use vinegar and water. I keep our land as clean as possible and use no chemicals on it. I didn't know this about ag urea and might have reason to use it someday. Thanks for sharing!
 

Hinotori

Sustainability Master
Joined
Nov 2, 2011
Messages
5,387
Reaction score
11,054
Points
373
Location
On the foot of Mt Rainier
I'm not sure it would work on comfrey. The stupid stuff grows in places I've had chickens penned.

If it works on some plants, it's well worth it though. Invasives suck.
 

Britesea

Sustainability Master
Joined
Jul 22, 2011
Messages
5,676
Reaction score
5,732
Points
373
Location
Klamath County, OR
it's worth a try. I wish there was something to take out quackgrass. Seems like the best way is solarization, but that's not practical in my garden because I would have to cover the raised beds AND the pathways with separate pieces of plastic. It also would drive off all my beneficial nematodes and worms and such.
 

Joel_BC

Super Self-Sufficient
Joined
Nov 21, 2011
Messages
1,284
Reaction score
318
Points
227
Location
Western Canada
I'm not sure it would work on comfrey. The stupid stuff grows in places I've had chickens penned.

If it works on some plants, it's well worth it though. Invasives suck.
True, and I haven't tried the method yet. Just from my observations of knapweed over many years, I believe it would work with that. I'll have to try it next year and report my personal experience.


Britesea, quack grass (or "couch grass") is a big problem in our region too. I did try solarization for a section of our big garden one year, and it worked really well. Knocked it back for several years, and good organic/bacterial activity & earthworms came back, once given normal organic practices again. But I understand the difficulties you'd face trying to do it with a raised-bed garden
 
Last edited:

Mini Horses

Sustainability Master
Joined
Sep 2, 2015
Messages
7,073
Reaction score
14,459
Points
352
Location
coastal VA
Have you considered using extreme heat? I have a dragon torch and it does kill out many plants that I would otherwise have had to dig and/or chemicalize.. Not always a "one time" cure but has helped me with some invasives. Fast and simple to light up and walk along hitting what I need gone.
 

Hinotori

Sustainability Master
Joined
Nov 2, 2011
Messages
5,387
Reaction score
11,054
Points
373
Location
On the foot of Mt Rainier
Quack grass goes too deep I think for the weed dragon. I'm glad I don't have it here. Mom does because some moron thought it was a good grass to plant in all the yards when they developed the housing area there in the 70s. I have horrid memories of digging it out of the garden and flower beds by hand.

Fire works on horsetail if you scorch it every two weeks during growing season for a couple years. Not much works on horsetail.

Scotch broom needs to be dug out when noticed. If it's a large area where digging isn't feasible (common here), cut it to the ground and mow every few weeks for a couple years.

Blackberry is a cut down and mow every few weeks as well, or keep goats with it on a rotational plan like most do here.

Bindweed is a pull it out once a month or so until the root is dead.

Yellow flag has to be dug out since it likes wet ground.

Canary grass will die back with constant mowing over several years, if you can mow it since it also will happily grow in wet soil. Can't dig that crap out
 

flowerbug

Super Self-Sufficient
Joined
Oct 24, 2019
Messages
6,173
Reaction score
11,723
Points
297
Location
mid-Michigan, USoA
bare ground can be covered with a few layers of cardboard. best way to smother things. eventually the cardboard turns into worm food. if you need to apply a second or third time it's cheap enough and quick enough. can be mulched over if you don't like looking at it.
 

Britesea

Sustainability Master
Joined
Jul 22, 2011
Messages
5,676
Reaction score
5,732
Points
373
Location
Klamath County, OR
I finally have my family trained to save every scrap of cardboard. I have a special bay just for the cardboard until I can use it somewhere... I figure if the worms start breaking it down in there it's free compost.
 
Top