Organic vs Synthetic Weed Control

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Apr 24, 2020

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Weeds are the bane of any homeowner’s existence. It seems like if you’re not pulling them every weekend, you’re dousing them in chemicals to eradicate them. While these chemicals are effective, you may wonder what they’re doing to your body or your outdoor pets.

This concern has led many amateur gardeners and weekend landscaping warriors down the path of organic weed control. Is organic weed control better for your turf and your health? We explore all that and more below.

Organic Weed Control Defined

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The term “organic” gets tossed around a lot. In the world of groceries, it means the food has been certified grown without synthetic fertilizers and without genetic engineering. In the case of meats, it means the animal was fed only organic foods. But going with organic weed control isn’t like rolling into the local Whole Foods and grabbing an organic steak.

Instead, “organic” in the context of weed control is an unofficial and lightly regulated term that refers to a natural remedy. Instead of reaching for a chemical produced in a lab, you resort to something present in nature with a similar impact as the chemical.

Amateur gardeners and homeowners often think of natural or organic products as safer. While it is true that organic herbicides are generally safer than synthetics, there are plenty of highly toxic organic lawn care products on the market, according to Ohio State University.

Organic weed control options range wildly from a concoction of soap, water, and lemon you can cook up at home to a pre-mixed store-bought product. The former is generally inexpensive and can serve multiple uses – you can use that leftover lemon in your post-yard-work tea. The latter often costs more than its synthetic counterpart and has a single use: killing weeds.

Pros of Organic Weed Control

  • Generally safer to apply in high-traffic areas
  • Some serve multiple uses around the home
  • DIY options are often cheaper than synthetics

Cons of Organic Weed Control

  • Limited effectiveness
  • Store-bought organics are pricier than synthetic options
  • A false sense of security
  • DIY options are generally nonselective

Synthetic Weed Control Defined

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Synthetic weed control is most of what you’ll see on store shelves. Scientists cook up these mixtures of chemicals that kill a wide range of weeds. In many cases, these synthetic herbicides are selective, so you can apply them to your yard to kill the weeds without harming your precious lawn.

Because these are cooked up in a lab with the key objective being weed destruction, the scientists behind synthetic weed control often give little thought to health concerns.

Of course, we’ve seen the health risks on a massive scale with the RoundUp class-action lawsuit, but these chemicals also have more localized health risks, including harming family pets if they walk on it too soon or triggering respiratory attack if inhaled.

Despite the risks, many homeowners and gardeners prefer controlling weeds with synthetics because they generally work faster and are more effective overall. Plus, many synthetic weed controls are designed to tackle multiple types of weeds, so you can buy one product and be done with it.

Pros of Synthetic Weed Control

  • More effective, in general
  • No precise mixing household items
  • Low cost and countless options

Cons of Synthetic Weed Control

  • Health concerns for pets and humans
  • Can harm other plants if used improperly

Pre-Emergent Herbicide

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When it comes to pre-emergent weed control – killing the weeds before they break the soil – there are effective organic and synthetic options.

Organic Pre-Emergent Herbicide

Pre-emergence is when organic herbicides tend to do some of their best work. The most common organic program for pre-emergent weed control is corn gluten meal. The short of it is the corn gluten meal suppresses the weeds before they can emerge from the soil, preventing them from ever being an issue.

The problem is corn gluten meal application is effective mostly in cooler climates and requires a relatively high application rate of 20 pounds per 1,000 square feet for 15 weeks of weed prevention. Even at that, corn gluten’s crabgrass control is only about 40% effective in its first year but can increase to 80% in subsequent years.

Corn gluten meal does, however, offer some nutritional benefit to your lawn, as it is 10% nitrogen by weight. On the flip-side, with only a 40% effective rate in its first year, you may be feeding the weeds too.

Synthetic Pre-Emergent Herbicide

There are numerous pre-emergency synthetic herbicides on the market, including those containing post-patent chemicals like oxadiazon, pendimethalin, prodiamine, and dithiopyr. Since these chemicals are post-patent, any company can create its own formula, driving the price down.

On top of a lower price, they are also 80% effective in crabgrass control for 90-150 days. With the right cultural controls in place, their effectiveness jumps to 95% or higher.

Post-Emergent Herbicide

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Like pre-emergents, there are synthetic and organic options in the world of post-emergent herbicides, too. However, there are special considerations when thinking about organic.

Organic Post-Emergent Herbicides

Some people may claim there are no effective organic post-emergent herbicides, but they are incorrect. There are several post-emergent organic herbicides that work very well against broadleaf weeds, including sodium chloride and chelated iron.

Chelated iron has actually shown superior in speed and effectiveness, as it’s displayed 100% dandelion control after just 24 hours. It’s also shown similar results on white clover, plantains, and ground ivy.

The downsides to chelated iron include its high price and struggles with perennial broadleaf weeds. While it shows an immediate impact on all broadleaf weeds at first, chelated iron fails to reach the root system, allowing perennial weeds to rebound after about three weeks. You can control perennial weeds with it, but it takes reapplication every three weeks.

Sodium chloride, which is just a salt mixture, is effective in controlling broadleaf weeds, but Ohio State researchers found its effectiveness varied. Also, researchers found its selectiveness isn’t as tight as chelated iron or a synthetic, so it could harm your turf.

Organics herbicides’ big struggle is the post-emergent control of sedges and grasses. There are organics marketed to control these weeds, but they are either nonselective and will kill your grass too or lack third-party testing to back up their claims.

Synthetic Post-Emergent Herbicide

Synthetic post-emergent herbicides have a huge advantage in controlling sedges and grasses, as years of data back up their ability to control these tough weeds. In broadleaf control, synthetics have a far narrower gap.

When battling dandelions, research shows synthetics are about 90% effective and control for 60-80 days. The struggle comes when tackling ground ivy and knotweed, as synthetics are far less reliable than chelated iron.

Verdict: Organic Vs. Synthetic Weed Control

In the end, should you use organic or synthetic weed control? It depends.

When Organic Makes Sense

Organic makes sense in a handful of situations. First, if you’re dealing with a nasty broadleaf outbreak, organics, like chelated iron, have proven quicker and more effective than synthetics.

If you don’t mind the several-year ramp-up period of effectiveness, organics also make perfect sense as a pre-emergent. Laying corn gluten meal may prevent only 40% of crabgrass from emerging in its first treatment, but it gets up to 80% in a few years and feeds your lawn without harmful chemicals.

Finally, if you live in an area that’s banned all synthetic herbicides or has a selective list of banned herbicides, your only choice may be the organic route.

When Synthetic Makes Sense

If you live a busy life and need immediate results, synthetic pre-emergent herbicides are the better bet. They not only show 80% crabgrass control in their first application, but the effectiveness flies past 95% with the right cultural practices, like a thick lawn and proper nutrition.

When dealing with grasses and sedges, synthetics are really your only post-emergent options. Also, when your budget is tight, synthetics are almost always the more pocket-friendly choice.

Get Your Healthy Lawn Organically or Synthetically

Whether you prefer synthetic weed control or organic, you now have the ammunition needed to know which is best for a range of situations. In most cases, though, the best approach will be a mixture of the two.

Regardless of which you prefer, the time is now to start working toward a healthy lawn. The sooner you get started, the sooner your turf will be the weed-free envy of the neighborhood.