Corn gluten meal is a byproduct of the corn milling process, primarily used as a high-protein supplement in animal feed. In gardening and lawn care, it is used as an organic pre-emergent herbicide and fertilizer due to its nitrogen content.

Synergy is a granular product that is applied using a broadcast spreader. However, most spreaders cannot achieve the recommended application rate of 20 pounds per 1,000 square feet. To ensure accurate application, we use specialized Earthway commercial spreaders set to a full open rate.

To achieve the highest effectiveness in controlling weed germination, we recommend applying treatments in both spring and fall. The spring application not only fertilizes your lawn but also prevents the germination of weed seeds. It should be applied before weed seeds begin to germinate, ideally between March 1st and March 31st. The fall application helps to winterize your lawn by increasing the concentration of corn gluten meal in the soil. If you choose to have a fall application, we recommend applying Synergy again in the spring for optimal results. Using both fall and spring applications can achieve a 60% to 80% effectiveness rate in controlling weed seed germination, while a spring-only application has an effectiveness rate of 40% to 60%.

• Corn gluten meal can be moderately effective at controlling weeds in a lawn when used correctly, but its success depends on several factors. As a pre-emergent herbicide, it prevents weed seeds from developing roots after germination, effectively stopping annual weeds like crabgrass, dandelions, and foxtail before they establish. However, it does not control existing weeds or perennial weeds with established root systems.

  When applied at the right time—typically early spring for summer weeds and early fall for cool-season weeds—it can reduce weed seed germination by 60-80% over multiple applications. Results are not immediate; repeated, consistent use over 2-3 growing seasons is often necessary to see significant improvement.

  Factors such as timing, soil moisture, and application rate impact its effectiveness. Additionally, it requires a sufficient application rate—20 pounds per 1,000 square feet—to achieve the desired results.  Overall Corn Gluten Meal works best as part of a comprehensive lawn care plan that includes proper lawn watering practices and lawn mowing techniques.

  We tend to see the following weed control rates when using Corn Gluten Meal.  We find the best results in the lawns where the homeowners are also following our watering and lawn mowing recommendations.

  • First Year = 60% control rate
  • Second Year = 70% control rate
  • Third Year = 80% control rate
  • Fourth Year = 90%+ control rate

Posting a pesticide application flag is a legal requirement, even if the product used is 100% organic. This is mandated by the Department of Agriculture. Any product that claims to control weeds must be marked with a pesticide application marker.

Dandelions are biennial plants, meaning they germinate from seed in their first year and then continue to grow from their root system for one to two additional years. Because your lawn naturally has dandelions at various stages of growth, it is important to apply Synergy annually. Synergy only controls weeds that germinate from seed. Therefore, the first application of Synergy will not eliminate dandelions that are sprouting from an established root system. While patience is required when using corn gluten meal, it can be extremely effective when used regularly over a 2-3 year period.

Synergy is a pre-emergent weed control product, which means it prevents weed seeds from germinating and developing properly. However, it does not kill existing weeds. Additionally, since it may affect grass seeds, we do not recommend applying this product if you plan to plant grass in the next 2 to 4 weeks.

This product is an organic pre-emergent, which means it will not prevent all weeds from germinating—only those that grow from seeds. If used in combination with One Earth Weed Killer as part of a full season program, you can expect to achieve a mostly weed-free lawn within a year, provided you also follow proper cultural practices like mowing and watering.

Instant results are not something that Synergy can guarantee. If you are looking for a completely weed-free lawn after just one application, it’s important to understand that organic lawn care is a gradual process. However, with patience and consistent effort, this program can be very effective.

To effectively control weeds, Corn Gluten Meal should be applied at a rate of 20 pounds per 1,000 square feet or more. In comparison, most chemical fertilizers are typically applied at a rate of only 2 to 4 pounds per 1,000 square feet, meaning that a greater quantity of product is needed when using Corn Gluten Meal.

Yes, corn gluten meal is rich in nitrogen, containing about 10% by weight. This makes it a beneficial slow-release fertilizer that can help promote healthy grass, stimulate microbial activity, and promote plant growth while controlling weeds.

You can use corn gluten meal in vegetable gardens, but caution is needed. Since it inhibits seed germination, it should not be applied where you plan to sow seeds. It’s best used around established plants or transplants to control weeds without affecting your vegetables.

Note that Organo-Lawn will not apply any product to vegetable gardens, but we do sell bags of Synergy for homeowner use. 

It is possible but unlikely. Organic nitrogen sources like the one from Corn Gluten Meal can leach into the water supply under rare conditions, though the risk is dramatically lower compared to synthetic nitrogen fertilizers. Organic nitrogen sources, such as compost, manure, or plant-based materials (e.g., alfalfa meal), release nitrogen only through microbial activity. This gradual release dramatically reduces the immediate risk of leaching and if leaching does occur it is only a fraction of the total nitrogen. 

Unfortunately, 99.7% of the corn produced in the U.S. is not organically grown. While there is organic corn gluten meal available, it is priced at four times the cost of conventional options. This high price makes it prohibitive for most people to purchase.