How does weed killer work?
All plants require sunlight to grow. Plants absorb sunlight through their leaves and by the process of Photosynthesis turn sunlight into sugars the plant can use for growth. Weed killer stops the process of photosynthesis thus killing the weed. Therefor weeds are killed quicker in the summer than in the winter due to the difference in sunlight. Weed killer must be applied to the leaves of the plant not the roots.
