Yes - there is a pre-emergent weed preventer called Preen that works well to keep weed seeds from sprouting. You can even find Preen for Vegetable gardens made from corn meal that will keep weeds from sprouting in the pathways around your veggies. You wrote that you have \"black cover\" so I assume you put down a weed block fabric with mulch on top. This will not stop the weeds because the seeds blow in and land on top of the mulch. You must first remove all the present weeds, than sprinkle the Preen right from the container and than you are done. It lasts for about 3 months. If you want to kill the weeds without pulling them you can spray them with RoundUP or smother them with several layers of wet newspaper and than a mulch. Try to enjoy the weeding experience if you hand weed or use a hoe - there is some instant gratification because just a half hour of weeding can make a huge difference in the looks of a garden bed. Keep growing, Marianne Binetti