Do you see why this picture of poppy seeds is so pretty? It is all colours of greenish-blue. The background is soft green and the poppy seeds are aqua-blue. However, to balance the blue you need the complementary colour of blue which is yellow.
Fork pom-poms, what a great idea and it involves less faffing than the cardboard rings or the wrapping of yarn round the fingers method. Eskimimiknits has written a tutorial on her fork-pom method which you can see in full here.