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How to Have a Weed-Free Landscape

February 2007

As spring approaches, the weed battle will heat up. You’ll be bombarded with ads for weed control products. I hope I’ve convinced you to ignore the claims of the chemical pushers. I also must pass on some facts on organic weed treatments.

Corn gluten meal (CGM) is our only known natural pre-emergent weed control. Under ideal conditions, it keeps germinating seeds from forming roots. Sadly, researchers at the University of Iowa, where this phenomenon was discovered, have isolated and patented 4 components of CGM. Now these are licensed to producers. BINGO! A simple agricultural product is more expensive. And, if they keep up with their distillation and isolation of components, I’d guess that in a few years they’ll turn this organic product into something akin to a chemical. Corn is already the most genetically crop.

Again I ask, “Does Nature approve?” Instead of trying to figure out how to kill weeds, let’s consider why weeds pop up. In my 20 plus years of landscape management - more than half organic, I’ve learned that weeds love compacted. Soil deprived of oxygen and moisture can’t support beneficial microorganisms, earthworms and desirable plants.

Nature hates bare soil. Something will germinate. Yep! Weeds. Weeds are hearty beneficial plants with strong roots that drill down deep in the soil. Nature’s little aerators make paths for water and oxygen and draw up nutrients. Then they die adding organic material to the soil. Over decades they improve the soil until desirable plants can thrive. Who wants to wait decades for weeds to do their thing? Let’s short circuit the process.

I’m not impressed with CGM as a weed inhibitor. It’s 50% effective if the temperature and ground moisture levels are perfect. After 1 inch of cumulative rainfall, its efficiency drops to zero. With 10% nitrogen content, it’s a fertilizer - at $25 per 40 lb bag, a very expensive way to fertilize weeds. I learned this by accident.

Years ago, CGM or rye over seeding were 2 of our fall treatments. We didn’t do both on the same yard. CGM would hinder germination. But, we hauled bags of both on the truck. Bags bust and we spill material. Inevitably, the two got mixed up on the truck bed. A few days after a hard rain, I saw little green sprouts growing right out of the CGM.

What? Grass seed sprouted in this “100% effective per emergent?” I found out that the university studies on CGM are done in very controlled environments - just the right amount of moisture.

Another thing most people don’t know is that CGM loses effectiveness over time. It must be put it out every 6 - 8 weeks over the growing season. But, if it’s too dry or too wet, it won’t work. There has to be better way.

I tested 3 products on my customers’ yards - manure fertilizer, meal-based fertilizer and CGM. CGM greened turf up most rapidly, but didn’t last. Manure fertilizer was slower on green up, but lasted longer. Meal based fertilizers was in the middle.

I tested these three plus a fourth, minerals, on 4 test plots - 1 on each side of a 5 sq ft buffer zone. The results on the 4 test plots were as expected. The minerals faired the worst. But, to my amazement, the turf in my buffer zone greened up more rapidly and was much healthier throughout the season. It hit me like a brick. Some material from each of the test plots had drifted onto the buffer zone. Combining ingredients was the key!

Biodiversity is a key principle of organics. Can you attract a diverse population of beneficial organisms with a single amendment to your soil? If a restaurant offered a single entrée, would it attract a lot of diners? If you set out a buffet with 4 or 5 entrées, you’d attract more. And is you offered 25 entrées, you’d attract a much wider group of people.

These results led me into making our special blends that work so well. I started out with 5 to 10 ingredients and kept going. We’ve just had our most successful year ever under the worst conditions since I’ve been in the business. Our level of customer satisfaction has been through the roof. We now put a minimum of 25 ingredients in our Spring Blend soil amendment. We’re not fertilizing the grass. We’re attracting a diverse population of microorganisms.

When you buy organic soil food, turn the bag over. Check the ingredients list. If there aren’t at least 10, put it back. It was produced by people more interested in making a profit than improving your turf.

The next big red flag is poultry litter. If it’s listed in the top few ingredients, put that bag back. Poultry litter is common because it’s cheap. Its poop filled with antibiotics and hormones. Webster defines antibiotic as “tending to prevent, inhibit, or destroy life.” - contrary to all we’re trying to achieve.

So, aerate and apply a good quality blended organic soil food at the rate of 20 lbs per 1,000 sq ft every 8 to 12 weeks. You’ll be rewarded with a healthy relatively weed-free landscape.