DIY Rainbow Petal Cake

You may have seen the DIY Rainbow Sprinkle Cake that we featured last fall.  Just possibly.  Maybe?  As it made its way around Pinterest and back.  In case you missed it, let’s just say it was absolutely fabulous and one of the top posts from 2012!  So needless to say, we’re quite excited because the talented baker behind the sprinkle cake tutorial… is back again today!  With another straightforward and totally achievable DIY.  Kate Wagner of The Greedy Baker is using everyday items to decorate a spectacular rainbow cake, perfect for any celebration.  It’s vivid, bright and has us cheering for a supply list including zip lock bags and spoons.  And once you see how easy it is, you’ll be cheering too!  It’s a DIY Rainbow Petal Cake!

DIY Rainbow Petal Cake  |  by Kate Wagner  |

This style of cake decorating is super simple yet incredibly effective.  Most importantly it doesn’t require any fancy decorating equipment, just every day items found in most kitchens.  So grab a spoon and let’s get started!

DIY Rainbow Petal Cake  |  by Kate Wagner  |

a DIY by Kate Wagner


  • 6″ crumb coated cake, chilled.
  • Cake board or plate
  • Skewer / Toothpick
  • Ruler
  • 3 cups Buttercream
  • Icing / Frosting food color
  • 6 zip lock bags
  • A teaspoon
  • Paper towel
  • Scissors
  • Turntable (optional)
  • 6 glasses/cups


STEP ONE:  Take your chilled, crumb coated cake and place on your turntable. Measure the height of your cake and using the skewer or toothpick mark mid height all the way around, holding the skewer against the ruler for a guide. This cake was exactly 4″ therefore the marking is at a height of 2″. This marking will be your guideline to help keep you piping dots in a consistent and even manner.

STEP TWO:  Divide the buttercream into 6 x 1/2 cup amounts. Tint buttercream as desired. For this tutorial the ‘Electric’ range of gel colors by Americolor were used. Fill the zip lock bags with each individual color and snip off roughly a 1/4″ from the tip of each bag.

STEP THREE:   Place each bag of buttercream into a glass and line them up in the order you wish to pipe. This simple tip will keep your workspace tidy as well as helping you keep track of the color order.

STEP FOUR:  Pipe your first row of dots onto the cake. Use the guideline to help get even sized dots by piping 3 dots above the line and 3 dots below.

STEP FIVE:  Take the teaspoon and using the back gently swipe each dot evenly to the right or left. Using the paper towel clean the teaspoon between each swipe so that the colors stay separated.

STEP SIX:  Continue to pipe and swipe rows of dots. Stop and check that you’re keeping a nice vertical line every few rows.

STEP SEVEN:  When you have reached your starting point finish up with a row of unswiped dots. This will be the back of the cake.

STEP EIGHT:  At this point chill the cake for 10 minutes before starting on the top. Once chilled, pipe a circle of dots around the outer top edge and swipe into the center.

STEP NINE:  Continue in this manner until finishing with a single dot of color right in the very center. Alternatively you might like to finish the top in a snail style, swirl pattern. In this case you would start again from the outer edge, pipe a single dot, swipe and repeat until you’ve reached the center. Again finish with a single dot.

STEP TEN:  Step back and admire your rainbow creation.  Then serve and enjoy!


DIY Rainbow Petal Cake  |  by Kate Wagner  |

Have fun with this simple buttercream technique by changing up the colors and patterns – there are so many design possibilities!

Cake & Tutorial:  Kate Wagner of  The Greedy Baker

Carrie Sellman , Founder & Editor

Carrie Sellman is the Founder & Editor of The Cake Blog. Her work has been published in BRIDES Magazine, Country Living Magazine and featured online at People, Today, Cosmopolitan, Glamour, Redbook, Real Simple, TLC, The Cooking Channel and more.


  1. 3

    DeniseB says

    This is beautiful!! I agree, I dont think I would be able to cut in to it!! Beautiful!! Wonderful Imagination!!

  2. 4


    This is darling. My daughter’s 24th birthday is this week and I would love to try this. It’s so colorful I know she would love it. So you simply cut off the tip and then use the back of the spoon to smooth the icing? No special tip needed?

  3. 8


    Wonderful tutorial for a gorgeous cake!! I wish I had this tutorial when I tried to use this method to ice my daughter’s 25th birthday cake in May! It really is easy to do with the correct directions. :) The one comment I would add is that it is important that the buttercream is thick. Mine was not thick enough and drooped on the cake. I made the inside polka dotted to match the frosting and it was a huge success (despite the droopy frosting). :) I am pinning this!

    • 10

      Susan says

      Amy, a crumb coat is a thin layer of frosting you put on the cake first. As in step one. You then put the cake in the refrigerator to harden up a bit. Depending on where you live, and your frosting, that could take 30 mins. The “crumb coat” helps prevent any crumbs from getting into your frosting when you are decorating. There are tutorials online. I hope this helped.

  4. 15



    This is AMAZING!! So amazing that I want to try make it this weekend.
    Just wondering… what actual cake would you suggest for this? Thanks heaps!

    • 16

      Carrie Sellman says

      Diana – inside was a funfetti cake. But any flavor you choose would work equally as well! Happy Baking!

  5. 17


    Just used your cake decorating style to make my youngest child’s first birthday cake! It’s not as darling as yours, but so very sweet! Excited to cut into it tomorrow. Thank you:)

  6. 18

    Anne says

    That’s a really cool looking cake. I was planning to do this for my friend’s birthday cake, but do you think this would work with store bought frosting straight from the container? Or would I have to thicken it somehow? Thanks.

  7. 22


    My daughter made a 6-inch Bride and Grooms cake for my sons wedding this past weekend using this method. A simple white cake with layers of lemon crud and raspberry jam. She used a normal buttercream recipe and put light purple and white roses on top. It was beautiful and only took about 10 minutes to decorate. This will definitely be the way we go when making fancy or fun cakes! Thanks.

  8. 23

    Rebecca says

    Would cream cheese frosting work? I’m making this for my friends birthday as a surprise and I’m practically ripping my hair out not knowing how the frosting will work, if at all :/

  9. 26

    Christina K. says

    Amazing cake and tutorial, thank you for sharing your talent!!

    The 6inch cake, how many layers of cake did you use and what was the depth of the cake pans? Hope to make this for my daughter’s 6th painting birthday party, and plan to do a test cake before party day.

    Many thanks.

  10. 27


    Stunning Cake!! Thank you for such simple and clear instructions. This will be the cake for our daughter’s first birthday. It will be beautiful in her photos and (once she gets her tiny hands into it) a beautiful mess!

    Thanks so much!

  11. 28

    Kristin Bucklen says

    Hello ! Your cake is beautiful! Would you mind sharing your recipe for the buttercream frosting you used with this cake? THank you!

  12. 31


    Well I never made this for my daughters bday but still plan to make this. I was just reviewing the directions and have one question that would seem obvious but I don’t want to guess.

    If I swipe to the left of my first row, I’m assuming I would add my next row of dots to the right side of that row. However when thinking about that it makes me wonder if I’d mess up the previous row. If I put the next set of rows to the left of the first swiped I would mess up the tips of the previous row. So please explain where I put the second row if my swipes go to the left. Thank you.

  13. 35

    Annie Jane says

    So cute!! Will make for my
    Baby girls 2nd birthday later this month. Is there a crumb covered cake recipe? For the base of this cake? Thanks!


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