Weed in mulch soil
Use sheet mulch. This is an effective way to eliminate weeds in an outdoor growing area. Cut down or mow all the weeds to the ground, leaving the severed weeds in place. Cover the area with flattened and overlapping sheets of cardboard, ensuring no light gets through any cracks in the cardboard layer. Without access to light, pests, pathogens, and weeds will die and no longer threaten your cannabis. Place a 3-inch (7.5 cm) layer of organic mulch on top of the cardboard—do not use nutrient-rich compost, which can reintroduce weeds. Within a year, the cardboard-covered and mulched weeds will be dead, the cardboard will have decomposed, and you’ll have a new growing bed.
Hoe or pull weeds. Hand weeding is effective when removing weeds around plants that you don’t want to disturb. Try to get rid of any annual weeds before they set seed. Some weeds, however, are perennials that grow from underground rhizomes, and each tiny piece you leave in the ground grows into a new weed. So keep at this task.
Use a germination inhibitor for growing seed cannabis
Use a germination inhibitor. Inhibitors, such as corn gluten, prevent seeds from germinating. These inhibitors affect only seeds, not established plants, and will not affect the underground rhizomes of perennial weeds. The inhibitors will also keep
Marijuana seeds or vegetable seeds germinate just as effectively as they do with weed seeds. Use inhibitors only on the bare ground after you’ve hoed and pulled the existing weeds. Non-GMO corn gluten is available from organic garden centers and Internet suppliers.