I am guessing your plants are being eaten by a small green worm that is hard to see. To be sure of the diagnosis use a magnifying glass to check partly eaten leaves to find the worms or the tiny black scat left behind. There are many types of butterfly and moth larvae that cause this type of defoliation damage but all can be controlled by a pesticide containing Bacillus thuringiensis which is considered a natural control method. Handpicking and a strong jet of water to remove the pests can also help. Keep growing, Marianne Binetti