The Easiest Rhubarb Dump Cake You'll Ever Make (Just 5 Ingredients!)

You know those recipes that sound too good to be true? This rhubarb dump cake is one of them — and I say that having been genuinely skeptical the first time I made it.

I'd been sitting on a massive bag of rhubarb from my neighbor's garden (she literally left it on my porch — bless her heart), and I had zero motivation to make anything complicated. It was a Tuesday evening, Emily had after-school activities, and my brain was completely checked out. So I pulled up the simplest thing I could find and just… made it.

Thirty minutes of hands-off baking later, the whole kitchen smelled like strawberry rhubarb heaven. Emily came home, took one bite, and asked me to make it again the following weekend. That's basically her highest rating system.

This easy rhubarb dump cake recipe is exactly what it sounds like — you dump everything into a pan, pop it in the oven, and walk away. No mixing bowls. No measuring cups for the batter. Just layers of fresh or frozen rhubarb, strawberry jello, sugar, cake mix, butter, and water. Done. If you love rhubarb-forward desserts, you might also want to check out my Bourbon Pecan Peach Crisp — same cozy, effortless energy, just with a different fruit.

Jump to:

• Why You'll Want To Make This Rhubarb Dump Cake Again And Again
• Ingredients For This Simple Rhubarb Dump Cake
• How To Make Rhubarb Dump Cake Step By Step
• How To Store And Reheat Your Rhubarb Dump Cake
• Variations And Tips For The Best Rhubarb Dump Cake
• Frequently Asked Questions About Rhubarb Dump Cake
• Recipes You May Like
• Let's Wrap This Up
• Rhubarb Dump Cake

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Why You'll Want To Make This Rhubarb Dump Cake Again And Again

• Only 5 minutes of prep — I timed it. Literally five minutes.
• Works with fresh OR frozen rhubarb, so you're not stuck waiting for spring
• No mixing required — this is the whole point of a dump cake, and it never gets old
• Feeds 12 people, making it perfect for potlucks or family gatherings
• That strawberry jello touch gives it a gorgeous pink color and a fruity sweetness that balances the rhubarb tartness
• Better after chilling — which means you can make it the night before and be a total legend the next day

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Ingredients For This Simple Rhubarb Dump Cake

Here's everything you need — and yes, the list really is this short:

• 4 cups sliced fresh or frozen rhubarb (about 15–16 ounces — don't thaw if frozen!)
• 1 (3-ounce) box strawberry jello (or any red jello — raspberry and cherry both work great)
• ¾ cup granulated sugar
• 1 (15.25-ounce) box white or yellow cake mix
• ½ cup salted butter, melted (salted really is better here — trust me on this)
• 2 cups cold water

A quick note on the cake mix: yellow cake mix gives a slightly richer, buttery flavor, while white keeps things a bit lighter. I've made it both ways and honestly? Both are great.

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How To Make Rhubarb Dump Cake Step By Step

The instructions are so simple it almost feels like cheating — but the result is completely worth it.

Step 1: Prep Your Pan

Preheat your oven to 350°F. Lightly spray a 13×9-inch baking dish with cooking spray. That's it for prep.

Step 2: Layer The Rhubarb Base

Arrange the sliced rhubarb in an even layer across the bottom of the baking dish.

Sprinkle the strawberry jello powder directly over the rhubarb — no need to dissolve it first.

Then sprinkle the granulated sugar evenly over that layer.

Step 3: Add The Cake Mix Layer

Open your box of cake mix and sprinkle the dry powder evenly over everything. Don't mix it in — just let it sit right on top.

This is genuinely the most satisfying step because it looks like it shouldn't work, and then it absolutely does.

Step 4: Pour The Butter And Water

Drizzle the melted salted butter as evenly as you can over the cake mix.

Then pour the 2 cups of cold water over everything. Again — no stirring. I know it looks chaotic. That's fine. The oven does the work.

Step 5: Bake Until Golden And Bubbly

Bake for 45 minutes to 1 hour, until the top is lightly golden brown and you can see the rhubarb bubbling around the edges. That bubbling is your sign that it's ready.

(My oven runs a little hot so I check mine at the 40-minute mark — just something to keep in mind depending on your oven.)

Step 6: Chill Before Serving

You CAN serve it warm, but honestly — let it chill in the fridge for at least 2 hours first. It sets up so much better and slices way more cleanly.

Serve with whipped cream or a scoop of vanilla ice cream. Non-negotiable, in my opinion.

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How To Store And Reheat Your Rhubarb Dump Cake

This cake actually keeps really well, which is great news if you're making it ahead.

• Fridge: Cover the baking dish with plastic wrap or transfer slices to an airtight container. It keeps well for up to 4 days.
• Freezer: Wrap individual portions tightly in plastic wrap, then foil. It freezes well for up to 2 months.
• Reheating: A quick 20–30 seconds in the microwave brings it right back to life. The texture stays nice and soft.

One thing I noticed — it actually tastes even better on day two. The flavors sort of settle and come together overnight, so don't be surprised if the leftovers are somehow better than the original serving.

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Variations And Tips For The Best Rhubarb Dump Cake

Have fun with this one — it's really hard to mess up.

• Swap the jello flavor: Raspberry or cherry jello both work beautifully. I tried raspberry once and it was honestly really good — a little more tart, which I loved.
• Add strawberries: Mix in 1–2 cups of sliced fresh strawberries with the rhubarb for a classic rhubarb strawberry jello cake situation.
• Use a spice cake mix: This sounds weird but it actually works really well in fall. The warm spice notes play nicely against the tart rhubarb.
• Don't skip the cold water: I made the mistake once of using warm water (don't ask), and the top didn't crisp up the same way. Cold water really does matter here.
• Cut the butter evenly: The more evenly you drizzle the butter, the more even the browning on top. I use a spoon to spread it around if it clumps.

Want to know the one thing that trips people up? Over-worrying about the layers looking "wrong." They're supposed to look messy before they go in the oven. That's the whole thing with a dump cake — the magic happens in the baking.

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Frequently Asked Questions About Rhubarb Dump Cake

Recipes You May Like

If you loved this easy rhubarb dump cake recipe, here are a few more crowd-pleasers to try next:

• Gluten-Free Apple Pie — another fruit-forward dessert that's just as simple and satisfying, with that same homey warmth
• Pumpkin Custard Pie — if you love a chill-and-serve dessert that looks way fancier than the effort involved, this one's for you
• Fudgy S'mores Brownies — because sometimes you need something rich and chocolatey after all that fruity goodness

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Let's Wrap This Up

This rhubarb dump cake is the kind of recipe I'll keep making for years — not because it's fancy, but because it's genuinely good and takes almost zero effort. Five minutes of layering, an hour in the oven, and a few hours in the fridge, and you've got a dessert that people actually ask for by name.

I've brought it to a neighborhood cookout, made it twice in one week (not my proudest moment, but also no regrets), and it disappears every single time.

If you try it, I'd love to hear how it went in the comments below! And if you're saving recipes for later, don't forget to pin this to your Pinterest boards — it's such a good one to have bookmarked for spring and summer gatherings.