Foxtail is a common annual grass weed that quickly becomes a problem in lawns and gardens. It reproduces exclusively by seed, with a single plant capable of producing thousands of seeds that remain viable in the soil for years. Effective management requires a two-pronged strategy: preventing new seeds from sprouting and aggressively eradicating established plants. Understanding the foxtail life cycle and its common species is the first step toward successful long-term control.
Identifying the Types of Foxtail
Accurate identification is important because different foxtail species respond differently to certain herbicide treatments. The three most common types are Green, Yellow, and Giant Foxtail, distinguished by the hairiness of their leaves and the shape of their seed heads. Yellow foxtail has long, wispy hairs concentrated near the base of the leaf blade. Green foxtail has a smooth, hairless leaf surface and an erect, cylindrical seed head that often displays a green or purple tint. Giant foxtail is the largest, featuring short, dense hairs along the upper surface of its leaf blade, and its large seed head characteristically droops when mature.
Preventing Foxtail Before It Sprouts
The most effective method for controlling foxtail is to stop the seeds from ever germinating through the use of pre-emergent herbicides. These products create a chemical barrier in the top layer of the soil that kills the seedling shortly after it begins to sprout. Timing is critical for success, as the application must occur before the foxtail seeds break dormancy in the spring. Foxtail seeds typically begin to germinate when soil temperatures consistently reach a range of 60°F to 65°F for several consecutive days. The ideal application window is therefore just before this, when soil temperatures are reliably between 55°F and 60°F.
Effective pre-emergent chemicals include active ingredients like prodiamine or pendimethalin, which provide extended residual control. Applying the product too late means the foxtail may have already begun to emerge, rendering the application useless. Once the granular or liquid product is distributed, it must be watered into the soil with at least half an inch of irrigation. This watering step is necessary to activate the herbicide and establish the chemical barrier.
Eradicating Established Foxtail
Once foxtail plants have emerged, they must be treated with post-emergent methods designed to kill the actively growing weed. For small infestations, mechanical removal through hand-pulling is a viable option. When hand-pulling, remove the entire root system and dispose of the plant before it produces bristly seed heads. Even a pulled plant can continue to ripen its seed if left on the ground.
Chemical eradication of established foxtail depends heavily on the surrounding vegetation. In areas like cracks in pavement or bare soil, non-selective herbicides containing glyphosate can be used for a complete kill. However, in turfgrass, a selective herbicide is required to kill the foxtail grass without damaging the surrounding desirable lawn. Selective post-emergent chemicals like quinclorac or products containing fenoxaprop-p-ethyl offer good control of young foxtail in many turf varieties.
Post-emergent applications are more effective when foxtail plants are small and actively growing, ideally before they reach the three-leaf stage. As the plants mature and develop a thicker cuticle, they become increasingly tolerant to herbicide absorption. Using a non-ionic surfactant with the herbicide mixture helps the chemical stick to the waxy leaf surface, enhancing treatment effectiveness.
Long-Term Cultural Control
Beyond chemical and manual removal, modifying the environment to favor desirable turf or landscape plants is a long-term strategy. Foxtail is a summer annual that requires sunlight to germinate, so shading the soil surface discourages its growth. Maintaining a healthy, dense turf canopy is the best natural defense against foxtail and other annual weeds. Achieve this by mowing the lawn at the highest setting appropriate for the grass species, typically between three and four inches.
Proper watering practices also reduce the opportunity for foxtail to thrive, as shallow, frequent watering encourages weed germination and weak turf roots. Instead, water the lawn deeply but infrequently, aiming for the top six inches of soil to be thoroughly moist. This encourages the development of deep-rooted, competitive turfgrass. Improving soil health through aeration and balanced fertilization further supports a vigorous lawn that can naturally outcompete foxtail for light, nutrients, and moisture.