Rhubarb Blueberry Oatmeal Bars

Blueberry Rhubarb Oatmeal Bars

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The blueberry squares at Starbucks are the inspiration for these Rhubarb Blueberry Oatmeal Bars. I had one of those a while ago, and it was delicious. And I knew I had to make a homemade version. Blueberries are in season now, and we had a bunch of sweet, juicy berries. And we also had rhubarb, so I decided to add that, too. Injecting a little bit of tartness was a good idea because blueberries and rhubarb were perfect together in these squares.

Blueberry Rhubarb Oatmeal Bars

It’s Okay to Have a Treat Sometimes

Can we call these rhubarb blueberry oatmeal bars semi-healthy? Yes, there’s butter and sugar. But they are made with fruit, and there are oats in there, too. But who am I fooling? These are a treat, no doubt about it. A delicious treat of blueberry rhubarb goodness between buttery oatmeal crispness. And we all need a treat sometimes. Life is about balance, and treats are part of that.

Two oatmeal bars sitting on top of a wooden cutting board

Blueberries are Great in Many Recipes

The best way to eat these fresh juicy blueberries, is of course, just straight up. At least for me. I can just plow through a bowl of these like they were peanuts. But I also like to showcase these luscious local berries in a recipe now and then, too. Like this Finnish Blueberry Pie, or Blueberry French Toast Casserole, or even in a savory dish like Blueberry Sourdough Sausage Stuffing, for your next holiday feast. You can even use these beauties in a cocktail. Try a Blueberry Ginger Martini, you won’t regret it.

A close up of a slice of oatmeal squares on a plate

Can You Freeze These Bars?

The answer is yes. These bars freeze very well. To freeze, allow them to cool completely, then flash freeze them on a tray until just firm. You can then pack the bars in an airtight container or bag. Or you can wrap them individually for a grab & go treat that will be defrosted by lunch or coffee time. 

A close up of a slice of oatmeal bars on a plate

Fun Facts About Blueberries

Did you know:

Blueberries freeze in only 4 minutes.

There are two types of blueberries; highbush, and lowbush. Highbush are the ones we buy in grocery stores and farmer’s markets. Lowbush blueberries are smaller and sweeter and are used in jams, pie fillings, preserves, etc. Get more blueberry facts here: 10 Fun Facts About Blueberries

Blueberry Rhubarb Bars



Squares of blueberry bars on a cutting board

Rhubarb Blueberry Oatmeal Bars

Blueberries and Rhubarb are delicious together in these oatmeal squares.
4.41 from 10 votes
Prep Time 30 mins
Cook Time 45 mins
Total Time 1 hr 15 mins
Course Dessert
Cuisine American, Canadian
Servings 24 bars
Calories 203 kcal


  • 3 cups fresh blueberries
  • 3 cups rhubarb cut into 1-inch pieces
  • juice of one lemon
  • 1 cup sugar
  • 4 tbsp cornstarch
  • 2.5 cups quick-cooking oats
  • 1 cup all-purpose flour
  • 1 cup brown sugar packed
  • 1/2 tsp baking soda
  • 1/4 tsp salt
  • 1 cup cold butter cut into cubes


  • Put blueberries and rhubarb chunks Into a large, stainless steel pot, over medium heat
  • Cook, stirring occasionally until rhubarb is softened.
  • In a small bowl, whisk sugar and cornstarch together
  • Add to fruit mixture, stirring constantly until thickened and smooth.
  • Remove from heat.
  • Heat oven to 350°. Prepare a 9 x 13 baking pan by spraying with cooking oil, or, lining with parchment paper.
  • In a bowl, combine oats, flour, brown sugar, baking soda and salt.
  • Using a pastry blender to cut butter into flour mixture until it resembles course crumbs
  • Press half the flour mixture into prepared pan to form crust
  • Spread blueberry rhubarb mixture over the bottom crust
  • Spread remaining flour mixture over the fruit layer, pressing lightly
  • Bake in center of oven until golden, about 45 minutes
  • Cool completely on a wire rack before slicing into 24 squares


Don't have fresh blueberries? An equal quantity of thawed frozen blueberries (unsweetened) will work fine in this recipe.
It's important to allow the bars to cool completely before slicing, so that they will hold their shape.


Serving: 1barCalories: 203kcalCarbohydrates: 31gProtein: 2gFat: 8gSaturated Fat: 4gCholesterol: 20mgSodium: 121mgPotassium: 108mgFiber: 1gSugar: 19gVitamin A: 260IUVitamin C: 3.1mgCalcium: 29mgIron: 0.8mg
Keyword Blueberries, oatmeal, rhubarb
Tried this recipe? What changes did you make?Let us know how it was!


16 thoughts on “Rhubarb Blueberry Oatmeal Bars

  1. I have frozen rhubarb and frozen blueberries what adjustments should i make in this recipe when using frozen?

  2. Looks delicious! I think your homemade version is much better and fresher than Starbucks! We love our blueberries too! Me and my son and easily chomp down a few pounds! Thanks for sharing! And I am going to buy some more blueberries! I love to freeze them at the end of summer so I can enjoy them during the winter months too!

  3. I have a TON of fresh rhubarb and a box of blueberries, and now I know exactly what to bake with them! Loving the combination of these fruits plus the oats!

    1. Hi Jessica! Isn’t it great having all this freshness to deal with? I’m constantly looking for ideas to use all the fresh produce. (not complaining :-))

  4. Blueberry and RHUBARB?! That’s a combination I haven’t yet tried but you’ve definitely convinced me to give it a go! Have a great weekend Colleen!

    1. Justine, yes, they are an amazing combo! I love how the rhubarb tempers the super sweet blueberries. I can think of a lot of other ways to use those two besides these squares. Enjoy your weekend, too!

  5. I hardly make squares, but now that I’ve seen these beauties I am excited to make some. Love the flavors! I agree, life is about balance, in life as in food.

  6. I must make these. My mouth is watering. Also the photography is so good, it’s not easy to take good food pics and you are excelling.

    1. Thanks Dina! These really are delicious. And thanks for your kind words. I love the photography aspect of blogging, and I’m always learning and striving to improve. So those words are very encouraging. 🙂

  7. I love squares and I really should make some soon. haha Your recipe sounds yummy, I might try using spelt flour. Yum!

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