Watermelon Fault Line Cake Tutorial

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Today I'm going to show you how to create a CUTE and simple Watermelon Fault Line Cake in buttercream!I love the fault line cake trend because there are so many fun & unique design possibilities!

We recently created a Sprinkle Fault Line Cake tutorial, and we're happy to bring you another fun design with today's watermelon version! 

Watermelon Fault Line Cake- Free Video Tutorial

Why We Love It

There are so many reasons to love this buttercream fault line cake design! Here are just a few!

  • Easy, no carving involved!
  • Versatile- We love this watermelon theme for summer, but the design options are endless!
  • All buttercream! We love any chance to create an all-buttercream cake design. 
  • This watermelon fault line cake is perfect for summer birthday parties, picnics, and more! Don't miss our full collection of favorite summer cakes!

 How to make a Fault Line Cake

Fault Line Cakes are so interesting and unique, and easier than you think to create!  

  • The basic idea for fault line cakes is to first crumb coat your cake, adding a thin layer of colors or sprinkles, etc. (often around the center of the cake but not always) wherever your "fault line" will be.


  • Next, build out the frosting around the fault line with a thick layer of frosting. This really brings this unique design together, giving it wonderful dimension. I find it easiest to pipe on the buttercream using a disposable piping bag with the tip snipped away. Then smooth with a bench scraper.

I love the look! We hope you'll give our watermelon cake a try. It would be perfect for summer gatherings!

Watermelon Fault Line Cake

More Summer Cake Design Ideas

This watermelon cake is great for summer! We've made many summer-themed cakes over the years. Here are a few of our favorite free cake tutorials!


Sharing the BEST Summer Cake Recipes, Tutorials, and Design Ideas

Favorite Summertime Cake Recipes

We also have a collection of our favorite cake recipes for summer! Whether you're looking for lemon cakes, strawberry cakes, cocktail-inspired cakes like Piña Colada Cake or Margarita Cake, we have so many fun and fruity cake flavors to share. Hop on over to see: The Best Summer Cake Recipes


A collection of the best cake recipes for spring and summer!


Enjoy the Tutorial!

Thanks so much for stopping by today! We hope that you will give buttercream fault line cakes a try. If you do, please leave a comment and photo below! We would love to see your work. 

Watermelon Fault Line Cake- Free Cake Decorating Video Tutorial

Watermelon Fault Line Cake- Free Cake Decorating Video Tutorial

Learn how to make a CUTE and trendy fault line cake with a watermelon theme in this free cake decorating video tutorial! Perfect for summer entertaining!


  • *We are decorating a double barrel cake in this video-- four 6-inch cake layers with supports in the bottom half, and a small cake cardboard halfway up.
  • Buttercream Frosting: We used our Fluffy Vanilla Buttercream. Our Classic Vanilla Buttercream is a good choice also. (A frosting that contains butter is my preference for fault line cakes).
  • Coloring Gels: I used Wilton Leaf Green mixed with a little Avocado Green for the dark green shade. I used Americolor Electric Green for the light green. (Use whatever shades of light and dark green you like.) . I used Americolor Red Red and Americolor Super Black also.
  • Bench Scraper and/or small offset spatula
  • Turntable- Optional, but helpful
  • Disposable Piping Bags


  1. After filling and assembling your cake, apply a thin crumb coat. Then, apply a thin red layer of frosting around the middle of the cake. Chill for about 15 minutes to firm up.
  2. Load your dark green and light green shades of buttercream to piping bags and snip the ends away.
  3. Apply alternating stripes of dark and light green on either side of the red frosting. I applied my stripes two layers deep so that it was thick.
  4. Smooth over the green striped frosting with a bench scraper. Chill for about 15 minutes or just until frosting is firm. Then go over again with a hot spatula or bench scraper, filling in any low points with more frosting. Frost the top of the cake green.
  5. Pipe on the seeds with a small round tip (tip 3 or 4)


You'll notice in the video that I chill my cake whenever I want to firm up the frosting. Firming up the frosting makes imperfections easier to correct, and whenever I use a hot spatula for smoothing, I like to apply it to chilled frosting. I also chill my cake in the freezer for about 15 minutes (or until firm) before moving it to the cake pedestal.

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