How to Use Glyphosate Herbicide? | The Right Way to Spray

Use glyphosate by spraying the actively growing leaves of identified weeds at the correct label rate, in calm warm weather above 60°F.

Glyphosate is a nonselective herbicide that kills most actively growing plants it contacts, but only when applied to green foliage. Spraying bare soil or stressed plants wastes time and money, and skipping the label guarantees poor results. The difference between a single clean application and a season of repeat sprays comes down to following a handful of simple rules grounded in how the chemical actually works.

How Glyphosate Works (And Why It Matters)

Glyphosate must be absorbed through green leaves and stems. Once absorbed, it moves through the plant’s vascular system and kills roots and shoots, making it especially effective against tough perennial weeds that regrow from root fragments. The most common mistake is spraying bare soil — glyphosate has no activity once it hits the ground. Spray foliage until uniformly wet but not dripping, then let the plant transport the chemical down to its root system. Target annual weeds when they are 10 cm tall or less for the most efficient control.

When Should You Spray Glyphosate?

Glyphosate kills best when plants are actively growing and not stressed by drought, cold, pests, or dust on leaves. Apply in warm sunny weather above 60°F with a calm breeze — never spray in high wind or during temperature inversions. Ensure no rain is expected for at least 1.5 to 6 hours, depending on your product’s label. The ideal window is between 9 am and 5 pm, when plants are actively moving nutrients. Avoid plants covered in heavy dew, wilted from drought, or showing frost damage.

How to Mix and Apply Step by Step

Start by identifying the weed species to choose the correct rate. For tough perennial weeds like bamboo, check our top glyphosate picks for bamboo to find a formulation strong enough. Always read the full product label, including instructions about adding a surfactant or adjuvant. According to UF/IFAS extension guidance, a 1 to 2 percent solution in water works for most landscape and nursery weeds. If the label calls for a nonionic surfactant (NIS), add it at 0.25 to 1.0 percent of the final spray volume. Fill the spray tank 80 percent full with clean water before adding the chemical, then add glyphosate and remaining water to reduce frothing. Spray leaves until thoroughly wet — fine droplets coating the surface, but stop before puddles form. Do not mow, pull, or dig treated weeds for at least a week. Within 7 to 14 days, the plant will yellow from leaf tips downward. For field applications, use 0.75 lb acid equivalent per acre for weeds under 6 inches, 1.13 lb for 6 to 12 inches, and 1.50 lb for taller than 12 inches; add ammonium sulfate at 8.5 to 17 lb per 100 gallons of water. Clean sprayers immediately with a 1 to 2 percent ammonia solution if switching to fungicides or insecticides.

FAQs

Can I spray glyphosate before rain?

Only if the rain holds off for the label’s no-rain interval, typically 1.5 to 6 hours. Rain within that window washes the chemical off leaves, requiring reapplication.

Do I need to add surfactant to glyphosate?

Check the product label — some formulations contain built-in surfactants. If required, use a nonionic surfactant at 0.25 to 1.0 percent of final spray volume. Never substitute dish soap or household detergents.

Is glyphosate safe to use around gardens and pets?

Keep spray off desirable plants, rinse accidental contact with water, and keep pets out until spray has fully dried.