Wet newspapers and put layers around the plants overlapping as you go; cover with mulch and forget about weeds. Weeds will get through some gardening plastic; they will not get through wet newspaper. Good composting!
Add 1 tsp. of liquid food coloring to 1 cup of water. Drizzle the colored water onto the soil surrounding the base of a plant. Wait 24 hours for the water to absorb. Apply another identical dose if the color change was not sufficient.