Glyphosate is a widely used, non-selective herbicide designed to control grasses, broadleaf weeds, and other undesirable vegetation. Since it is a concentrated product, it must be diluted with water before application to ensure effectiveness and manage application strength. The correct dilution rate is not a single, fixed number but varies depending on the product and the target weeds. This article provides practical guidance on how to determine the appropriate dilution rates for your needs.
Understanding Concentrate Strength
The amount of concentrated glyphosate required per gallon of water is directly proportional to the product’s active ingredient percentage. Commercial products are sold in various strengths, commonly ranging from 18% up to 53.8% active ingredient, with 41% being a common formulation. A higher concentration means a smaller volume of the concentrate is needed to achieve a specific strength in the final spray solution.
Before mixing, locate the percentage of the active ingredient on the product label. This figure is the foundation for all dilution calculations. Using a lower-strength product, such as an 18% formulation, requires adding a greater volume of concentrate per gallon of water compared to a 41% product to reach the same working strength. Always consult the manufacturer’s directions for the most accurate instructions.
Mixing Ratios for Effective Application
The ideal mixing ratio is determined by the type and size of the vegetation being treated. For most general weed control, a final solution strength of 1% to 2% is often sufficient. This range is effective for smaller annual weeds and grasses that are actively growing.
For a standard 41% concentrate, a general-purpose mixture for light weed control involves adding about 1.5 to 2.5 fluid ounces of concentrate per gallon of water. This mixture is suitable for routine maintenance and treating young, easy-to-kill weeds. Using the lower end of this range minimizes the amount of chemical applied while still achieving control.
When targeting tougher, more established perennial weeds, brush, or vines, a stronger mixture is necessary to ensure the systemic herbicide is properly absorbed and translocated throughout the plant. For these resilient species, the concentration should be increased to about 4 to 5 ounces of the 41% concentrate per gallon of water. Some labels recommend up to 6.5 ounces per gallon for very difficult weeds, resulting in a 5% solution strength.
Stump Treatment
Stump treatment, used to prevent regrowth on freshly cut woody plants, requires a significantly higher concentration. This application involves painting the herbicide directly onto the cambium layer of the stump. Many labels specify little to no dilution, often calling for a 20% to 50% solution of the concentrate, which means mixing it with very little water or using it straight. Remember that these are general guidelines, and definitive mixing instructions are always found on the product label.
Safety Protocols and Proper Disposal
Handling and applying the mixed glyphosate solution requires adherence to specific safety and environmental precautions. Personal Protective Equipment (PPE) is necessary whenever mixing or spraying the herbicide, as the concentrated form can cause serious eye damage. At a minimum, this includes wearing chemically resistant gloves, eye protection, and long-sleeved clothing to minimize skin exposure.
Avoid application on windy days to prevent spray drift, which can damage non-target plants. Glyphosate is a post-emergent herbicide with no residual soil activity, meaning it is inactivated upon contact with the soil. However, to protect aquatic life, care must be taken to avoid runoff into waterways, ponds, or storm drains.
Proper disposal of leftover mixed solution and empty concentrate containers is mandatory. Never pour unused solution down a drain or onto the ground, as this can contaminate water supplies. Leftover product should ideally be used according to label directions or the excess should be sealed in its original container and taken to a household hazardous waste collection event. Empty plastic containers must be triple-rinsed before disposal or recycling, following all applicable procedures.