Goat head weeds are found in many gardens and lawns. They usually grow in flat patches, but will grow upward in shaded areas. The leaves are flat and about a quarter inch in length. The flowers of the goat head weed are yellow with five petals and the seeds are hard with two to three sharp spines protruding, resembling a goat's head, and sharp enough to puncture car tires. You can eliminate goat head weed, but you must tackle it as soon as you see it growing, either by pulling the weed or using herbicides.
Uproot goat head weeds you find with a trowel, making sure you pull the entire root system as well as the foliage above ground. You'll have to gather all spiny seeds as well because they will germinate and regrow.
Place all the plant parts, roots, seeds, and foliage, into a bag and seal before throwing into the garbage. Goat head weed should not be composted because it will germinate in the composter.
Check frequently for new weeds to emerge. To kill this weed entirely, you'll have to remove every seed, which can survive for many years, and pull up roots every three weeks.
Spray an herbicidal product over the goat head weed before it blossoms, while still growing and thriving. Glyphosate, sold commercially in the herbicide Roundup, is a broad spectrum herbicide, which means it's non-selective and will kill most plant life it touches. It can be used on goat head weeds if there aren't other plants growing nearby.
Spray dichlorophenoxyacetic acid, (such as 2,4-D) when you find goat head weed on your lawn, as it will not harm your grass but can be effective against any broadleaf weeds such as goat head. Garden Guides recommends you spray these herbicides on a day when the temperature is between 60 degrees Fahrenheit and 80 degrees Fahrenheit and no rain is expected. Make sure you saturate the weed completely with the herbicide.
Inspect the area after spraying and gather any remaining seeds which can germinate if they survive, and lead to regrowth. You will also have to look for weeds that have survived in the ground and uproot them. Place them in bags and put them in the garbage.
Check frequently, every three weeks, for new growth and seeds. You may have to spray again before the growing season is over.