The plants could be lacking in nutrients or not getting enough sun. Potted plants need fertilizer, so use a balanced plant food such as Osmocote in the potting soil if you did not use a potting soil mix that included fertilizer. Do you see green veins in the leaves that are darker than the rest of the leaf? This could be the sign of a lack of iron in the soil. Certain plants have different nutrient needs, so some flowering plants will show signs of nutrient stress while others will not. Do not overwater as wet soil can prevent the take up of nutrients. Water only when the top one inch is dry to the touch. Keep growing, Marianne Binetti