How Much Light Is Too Much Light For Your Clones? Often, un-rooted clones receive too high of light intensity which can manifest itself in the form of yellow, cupped leaves. This usually occurs when light levels exceed 180ppfd as excess light will trigger increased photosynthesis, which in turn will increase the plant's demand for water and nutrient consumption. Because fresh clones have no roots, they are unable to uptake water and nutrients efficiently which will eventually lead to self-cannibalization and yellowed cupped leaves. Keeping light levels in the optimum range of 150-180ppfd will help you avoid this occurring!