Chlorophyll in vegetables is the key to making green food dyes. Kale, spinach, watercress can all be used to make green dye. Spinach is the most popular because it is basically tasteless. You may choose to boil or juice the vegetables. Another alternative is to use red cabbage.
Turmeric and Red Cabbage Method:
1/4 cup turmeric
2 cups red cabbage dye
Combine
Red Cabbage and Baking Soda Method:
Cut cabbage into strips
Cover with water
Boil
Cool
Strain
Add pinch of baking soda to turn the blue/purple into green