In this podcast, we talk organic weed control with Dr. Jeff Gillman. While currently the Director of the UNC Charlotte Botanical Gardens in Charlotte North Carolina, he’s spent his career getting to the truth behind the rhetoric in matters involving both the garden and the environment.

Jeff Gillman, Ph.D is a “joe gardener” kind of guy –
always searching for the benefits, drawbacks and bottom line behind any and every gardening hack out there.
Jeff holds a master’s degree in entomology and a Ph.D. in horticulture. He has worked as a Professor at the University of Minnesota where he taught and conducted research on a variety of horticultural topics including extensive work on organic weed control.
Organic Weed control is a never-ending battle no matter how you slice it. For organic gardeners, the finding methods to control weeds without the use of harsh synthetic chemicals has always been rather elusive.
However, one control method to fight broadleaf weeds in lawns and landscapes is an iron chelate product that is readily available in retail lawn and garden centers. The active ingredient is FEHEDTA and is marketed under several brand names. See the link towards the bottom of this post for more information and product names.
It’s often used as an iron fertilizer. When applied as an herbicide, the control overdoses broadleaf weeds with iron.
A common synthetic herbicide commonly used in lawns for broadleaf weed control contains an active ingredient 2, 4-D. The biggest concern Jeff cites in its use is the length of time is stays in the system of animals and pets.

Corn gluten meal is currently the only organic pre-emergence weed control available on the market. The key to success with it is proper timing and rate of application. Patience helps too. It becomes more effective over time. Photo by Laura Brandt.
For organic pre-emergence weed control, the only option currently is corn gluten meal. While it can be very effective under optimal conditions, consumers will get mixed results depending on where you live in the country.
A side benefit to using corn gluten meal is that it supplies enough fertilizer to feed your lawn for a year. The downside to corn gluten is that it is not very effective in the first year of use but the second year, and beyond, it controls about 80% of broadleaf weeds.
To be effective, you must use at 20 pounds per thousand square feet. It’s very safe and the only organic pre-emergence weed control currently available.
As for landscape beds and gardens, two of the best options currently available are:
Common vinegar (acetic acid) when topically applied, burns the tops but has little impact on roots. Be careful using this as it is deadly to frogs and amphibious creatures. Horticultural grade acetic acid is dangerous at 20% concentration. Jeff advises not to use it. It’s too dangerous and simply not worth the risk.
Clove oils and citrus oils are also sold as organic alternatives to synthetic herbicides. Their killing action is similar to vinegar and provides marginal success to weed control. If using any of the above options, it’s best to attempt control when weeds are young and small.
Flame Weeders, typically use propane canisters or backpack tanks to deliver a concentrated flame to weeds. To be effective, it often requires multiple applications. The heat only penetrates about ½ inch into the ground.
If you’re looking for total control with any of the above options, you’ll likely be disappointed, at least after only one application.
My protocol for a weedless organic lawn and landscape

To cut down on weeds in my lawn, I focus on promoting a healthy growing environment by building the soil with composted horse manure and Milorganite as an organic nitrogen source with iron. (Also note the use of mulch in all the landscape beds to control weeds there.)
Although my lawn may look weed-free, it’s not. But weeds are minimal. I attribute that to focusing on building the soil health and promoting the growth of the lawn for ideal conditions: mowing high, aerating the soil in fall, adding composted manure and Milorganite. Also, note the use of mulch in the landscape beds. Between the beds and the lawn, overall my weed challenges are minimal in my 3-acres of cultivated space.

I value the use of mulch so much for suppressing weeds organically; I use it in all my garden beds around the farm. There is nothing better to keep weeds under control than a two-inch layer of mulch.
The best organic method for controlling weeds in landscape beds is the generous use of natural mulch combined with dense plantings. I apply a two-inch layer of free arborist wood chips (or purchased natural mulch as above) over all exposed surfaces.
The difference in areas where I have mulch and where it needs to be added is dramatic. Weeds are few and far between in the mulched areas, vs. a constant battle in the exposed areas. If you need to be convinced that mulch works for suppressing weeds, try this experiment for yourself, and you’ll quickly become a fan of using mulch to control weeds naturally.

After many years of trying just about every tool on the market, I now reach for just one when heading out to do some weeding. My trusty scuffle hoe (aka winged weeder) provides the most effortless, and efficient results for me.
Even with the liberal use of mulch, weeds are a fact of life. Over the years, I’ve finally settled into a single tool I use nearly all the time for weeding my garden beds.
I’ve heard it referred to by several names, primarily the scuffle hoe (aka winged weeder). It allows me to easily sever roots from the top growth at the soil surface. I like it because I can stay in a standing position while slicing weeds from their roots with minimal effort.
The key to making this my tool of choice is finding the one with a high quality, sharp stainless steel cutting edge on all three sides. That, combined with a long handle which (for me) meets me at about my belt line.
For you, a higher angle of attack may be easier to work with. Personally, I’ve used ones like that where they meet my body at about mid-chest level. I don’t find those nearly as easy to use. Being able to keep your arms in a more relaxed, extended position is what I’ve found to be the most comfortable and effortless option.
Solarization is another method for killing weeds and weed seeds near the surface. Clear thick plastic placed over the soil surface and left in place for several weeks can be effective.
One of the temporary downsides of solarization is the loss of beneficial microbes living near the surface. Fortunately, once the plastic is removed, microbes will repopulate the area within just a few weeks.
Links & Resources:
Episode 002: Five Steps to Your Best Garden Ever
Episode 006: Weedless Gardening with Lee Reich
Episode 008: Organic Pest Control with Jeff Gillman
Corn Gluten Meal research by Iowa State University
The Truth About Organic Gardening book by Jeff Gillman
The Truth About Garden Remedies book by Jeff Gillman
Episode 314 of Growing a Greener World – Just Because It’s Organic, featuring Jeff Gillman
Episode 419 of Growing a Greener World – Garden Myths, featuring Jeff Gillman
Milorganite: Our podcast episode sponsor and Brand Partner of joe gardener®
2 Responses to “007-Organic Weed Control with Jeff Gillman”
Thank you Joe for showing us your shuffle hoe (or winged weeder.) I found one on-line and have been using it for a few weeks and I absolutely love it! While working out of town for a year, the invasive “creeping charlie” overtook my woodland garden. It’s tough to weed it out of the mulch. This tool easily gets under the wood chips and slices off the roots and I’m making a lot of progress! Before I tackle a new area I go back to areas already worked and shuffle through again to nip any new growth. No other tool has done what this one has. THANK YOU!
#iamajoegardener
That is awesome news Shirley! So glad you found one you like and you’re as happy with it as I am. It really is a pleasure to work with. Thanks for sharing your thoughts here.
Thank you Joe for showing us your shuffle hoe (or winged weeder.) I found one on-line and have been using it for a few weeks and I absolutely love it! While working out of town for a year, the invasive “creeping charlie” overtook my woodland garden. It’s tough to weed it out of the mulch. This tool easily gets under the wood chips and slices off the roots and I’m making a lot of progress! Before I tackle a new area I go back to areas already worked and shuffle through again to nip any new growth. No other tool has done what this one has. THANK YOU!
#iamajoegardener
That is awesome news Shirley! So glad you found one you like and you’re as happy with it as I am. It really is a pleasure to work with. Thanks for sharing your thoughts here.
Joe, I just re-listened to this podcast because there is just so much great info here. I’m planning to give the iron chelate a go on my lawn this year. I am wondering if you would give the brand and size of the scuffle hoe to talk about. I’m very interested in the one you pictured and there being several different brands out there (I have one I don’t care for) I am hoping you can narrow down my search. Thanks as always Joe for your great work! My one stop shop for trusted gardening info! – Jeri
Hi Jeri! Wow, no pressure here! Thanks for your confidence.
Unfortunately, I don’t know the name of the brand for my scuffle hoe. I’m as frustrated about that as you I’m sure. Whoever made it did not do a good job branding their product.
I do love the way this one fits to my body and the well made steel blade. Others have a bad angle of attack, cheap steel and a handle length that may be too long or short. I so wish I could identify the maker of my product. I’ve looked all over it and nothing there to say. But I’ll keep looking. Sorry about that Jeri. If I nail it down I’ll be sure to let you know.
Thanks for the response Joe. It’s alright that you don’t know what yours is. I’ll do some research and pick one I think will work. If I like it I’ll let you know! I appreciate you being there for your audience!
Hi Joe! Any ideas for weed control when the start sprouting up through large gravel paths and driveways?
Hi Laura. Yes, this definitely limits your options, and hand weeding or using a tool for that is pretty much off the table.
I would use (very carefully) vinegar through spray application, and paying close attention so as not to overspray any frogs, lizards, etc, or, you can use a propane “flame weeder”. This is likely the quickest solution and pretty fun too. It can be a little intimidating initially but the precision delivery of a tight flame is a great way to tackle weeds in a gravel driveway.
Good luck!
Thanks, Joe! I appreciate the advice here. Looking forward to tackling this!
I live on a lake. We have to be careful using weed killer or fertilizer because runoff can harm plants/animals in the lake. Also, fertilizers can create algae blooms in the lake and cause invasive weeds thrive off of fertilizer run-off. Is there any weed killer and fertilizer safe for pets and lake home yards?