I HAD to give this myth a try, and I found that there is still a way to dye lemons with food coloring. Just not as vibrantly. And NOT the whole lemon!
This is as good as you will get it. The Skin of the lemon will not soak up the coloring like the rest of it does.
All you do is slice up your lemons, pick your color & dump it into some water. Next, submerge your lemons into it and let them soak it up until you get the color you want (I let mine soak for about 30-45 minutes.)
One thing I learned was NOT to dump the food coloring on lemons without water. It will give the lemons uneven coloring. Instead, as shown in the picture with the blue lemons, submerge them completely in water that has an even distribution of food dye. If you do dump them onto the lemons raw, you will end up with a Pinstrosity!
As you can see in the right picture, the lemon skin turns a slight greenish color.
Wish it dyed the whole lemon!
One other tip, you should sponge off any excess food dye so it won’t change the color of your water too! You want those lemons to stand out!