How can weeds negatively impact turf and ornamentals?

Weeds can significantly impact turf and ornamentals by competing for resources such as water, nutrients, and light. This competition can lead to a reduction in the overall health of desired plants. When weeds proliferate, they can overshadow or outcompete ornamental flowers and turf grasses, causing these plants to become stressed or weakened. This can result in diminished growth, reduced flowering, and increased susceptibility to pests and diseases.

In contrast, the other options reflect benefits associated with certain plants or ecological functions that do not apply to the role of weeds in a garden or turf scenario. For example, while some plants may enhance a garden's aesthetic or provide habitats, weeds typically do not contribute positively and can instead detract from the beauty and function of cultivated spaces.