There are several brands of pre-emergence weed killer granules. One popular brand is Preen. Pre-emergence weed killers are applied to soil to keep weed seeds from germinating. They should not be used just before planting desirable seeds, as these may also fail to germinate.
About this Author
Marie Notnats enjoys learning about new topics and teaching people new skills. She has been writing professionally since 2008. She is a professional horticulturist with a Bachelor of Science degree in horticulture from Brigham Young University. She writes for About.com, Examiner.com, eHow, and assorted gardening blogs.