Blend the mixture for a minute. Peel them off and place in a blender, fill with water so it is 1/2 to 2/3 full. Apply spray to the foliage in the evening. Hold the spray bottle 6 to 12 inches (15 to 30 cm) from the … Strain the chunks of garlic out and put them aside. How to mix ingredients for backyard mosquito repellent spray: Break bulbs of garlic into cloves.