I haven't tried them yet, but will be trying them for my son's second birthday, so I can't tell you how well they work but India Tree's nature's colors see promising. Best of luck!

I recall seeing some fruit and veggie rainbow pancakes on this blog. I bet they could be adapted into a birthday cake.

I have searched long and hard for vibrant natural dyes for baking, to no avail. The ones I've found muted pastels, but nothing like the colors you get from FD&C red #5, unfortunately. I am sure there is a way (that someone more kitchen-savvy will suggest) to achieve this through pulverized beets, blueberries, basil, etc., but as far as what's on store shelves even in really high-end baking stores, I've come up with zero.

I used the india tree colors last year for a 4th of July cake. It turned out pink grey and blue grey. In other words, awful.

I just made the rainbow cake with gel food colors. I used Ateco which seemed slightly more natural compared to Wilton's, but still uses the scary red and blue dyes. If anyone can find a natural gel dye, that would be awesome. I tried.

I found this on pintrest the other day, it was the same rainbow cake colored using fruit instead of dye. Here's the link to it:
http://iammommy.typepad.com/i_am_baker/2010/04/mothers-day-garden-party.html

She even tells you how much fruit you'll need and how to do it. Hope this helps! I love the rainbow cakes and hope to make one for my daughter's first birthday! Good luck!

I have two children who are really sensitive to FD&C dyes. I would never give them to a baby. After seeing what they can do to our middle daughter, our whole family avoids them 100%. 45 minutes after ingesting even a cookie with a few M&M's, she goes from sweet, normal and loving to angry, meltdown prone, violent, having difficulty falling asleep and unable to stay asleep, and not able to focus. It lasts for 4-5 days and then she is back to normal. It is literally like someone has flipped a switch.

I don't think they have any place in our diet--they are petroleum based chemicals, not food.

That said, I have heard that beets and spinach are supposed to be good for making red and green dyes, but I have not tried either one. I believe that European countries use natural dyes in their processed foods. I am not sure whether they are anything that would be available commercially or in the US, but that might be worth looking into.

RachieP, I love that fruit rainbow cake you linked to. I can't wait to try it out. I never thought I'd be able to do a rainbow cake.

I did notice she said she added a few drops of food coloring. I wonder how it looks without them.

I made the I Am Baker rainbow cake last month for my daughter's birthday. Came out great! I was a little worried, as the batter is much lighter than the finished cake. But once we cut into it, it was amazing! Also, the layers aren't as thick as usual layers, so watch the bake time closely. (I added one drop of food coloring to each layer b/c they looked so pale as batter. I think you'd still have a lovely rainbow without the food coloring. Your red layer might be a little pink is all.)

I should add, with all the fruit, the cake was super moist and very delicious. One of the best layer cakes I've ever made.

Thanks everyone! I'm sold on the the I am Baker cake. Thanks for the link, RachieP, and the review, avimom!

I once tried to make red velvet cake with beet puree instead of dye and it actually turned out dark brown (almost black) and not the bright red you would think. It also tasted just slightly amiss. I can also tell you that spinach will turn brown during the cooking process. I experimented with natural easter egg dying and had fantastic success with red cabbage creating a reallly beautiful dark teal color so you might be able to come up with dye related to boiling cabbage. Also, I believe that tumeric (which is yellow) has no flavor but does create a vibrant yellow color. I see lots of experimentation in your future...good luck. If it were me, I think I'd forego dying the cake and stick with white cake and add color elsewhere (maybe the candles?). Or you could make a homemade confetti cake by just adding colorful sprinkles to a white cake. That's what i did for my son's first birthday party last year.
As for the babies' sugar-intake, neither of my sons were actually interested in eating much of their cake/frosting at their first party. It tends to be more of a tactile experience for them, so don't worry too much about it. If you fill them up on a delicious meal, they won't care that much about the cake anyway.

Why not make a trifle, instead?

http://www.epicurious.com/recipes/food/views/Raspberry-Lemon-Trifle-105181

You could do a layer of white cake, then a layer of fruit/jam/etc, then another layer of cake, or pudding. Lovely colors from the fruits, etc, and no food dyes needed!

Plus, you could get some of those adorable little jelly jars and make individual ones: http://www.amazon.com/Ball-Deluxe-Quilted-Jelly-Canning/dp/tags-on-product/B000PSAMJG and since the jars are almost impossible to break, little ones will be safe.

It's their birthday. Live a little.
Sheesh!

Here is my story when I made them with the India Tree brand:

http://suburbanhomestead.typepad.com/blog/2011/03/hippie-cakes.html

I can understand natural dyes, but it is one day every year. Letting them have a little sugar on their birthday won't hurt them. I know it's tempting to try to always be the super mom that cares more and does more than everyone else, but really, a little sugar doesn't hurt them on their birthday, and they love it! We didn't do a smash cake. We just gave ours a piece of birthday cake and she thought it was the best thing ever. She got it everywhere. It was so awesome.

This cake looks like a plastic toy, not food. It's unrealistic to expect to get a highly unnatural look with only natural ingredients. How 'bout serving a natural cake on colorful plates/ with colorful decorations instead?

I agree with the idea of fruit. I love the idea of accentuating cake with fruit. All I would recommend is doing a trail run to see what color fruits become when baked.