Goatheads are a tough adversary. A goathead vine can begin forming flowers and then thorns within 15 to 25 days.
Left unchecked the plant can grow 10+ feet in diameter and drop hundreds of thorns.
Each goathead has five thorns which holds two to four seeds. The thorns puncture bicycle tires and stick in shoes and dog paws. Seeds spread in the neighborhood and can survive 5+ years in the ground before sprouting.
Goatheads which are also called Puncturevine (Tribulus Terrestris), are an invasive noxious weed that originated in Eurasia. The growing season in the Wenatchee area is June through October. The plant grows more actively in higher heat (July/August), after rain storms and in disturbed soil.