Is there a "natural" herbicide that will prevent weeds from growing in cracks in patio?
Vinegar (white) with a squirt of dish washing liquid will work but may require repeated applications. Look for 10% vinegar where pickling supplies are sold. Avoid getting the vinegar on grass or any other plants. Early fall is the best time to apply the vinegar solutionon perennial weeds. Also apply when the weather report is for several sunny days so the solution will be more effective.