User blog comment:Milesprower2/Top 15 Best and Worst Plants/@comment-1764483-20150105202800/@comment-24828059-20150107194722

I tried it a lot of times and they do not stack. They probably added the green effect to show the combination between blue and orange? It wouldn't make sense if the zombies were just orange or just blue in a Sap-fling + Winer Melon/Snow Pea/Iceberg/Hurrikale combo.