Q.What to mix w/RoundUp in rainy weather to kill weeds?
What should I mix w/RoundUp to get RoundUp to stay on weeds in the rainy weather?
Spraying or applying an herbicide in rainy weather is really not recommended. You need to wait for a time of clear weather between the rainstorms. You can add what is called a Spreader-Sticker product to the spray mix to help it spread out over and stick to the foliage. Go to a local garden center or nursery and tell them you need a Spreader-Sticker product to add to your plant spray mixes. It also works very well for use in application of insecticides and fungicides.