Frozen Watermelon Hard Seltzer Slush
By Marty Cole · May 20, 2026
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Hottest day of the summer is when this Frozen Watermelon Hard Seltzer Slush earned its keep in the Ninja Slushi. Watermelon seltzer, vodka, watermelon juice, and lime freeze into a slushy, light, juicy drink that tastes like a melted popsicle you're not supposed to have. My cousin at the lake house called it adult Capri Sun and the name stuck for the rest of the weekend. Keep it to the 21-plus crew. The seltzer goes flat quick, so don't over-spin it, a shorter run keeps a touch of that fizz instead of pancaking it into syrup.
Your machine size
Slushi 64 oz (Standard) · quantities scaled ×1
Ingredients
- Watermelon Hard Seltzer24 oz
- Vodka4 oz
- Watermelon Juice12 oz
- Simple Syrup6 oz
- Fresh Lime Juice2 oz
- Lime Wheeloptional1 garnish
Makes ~52 oz · est. 3.3% ABV
Directions
- 1Let the hard seltzer go slightly flat, then stir with the vodka and juices.
- 2Add the simple syrup since seltzers are low in sugar and need it to freeze.
- 3Pour the mixture into the Slushi vessel below the max line.
- 4Lock the lid and choose the SPIKED SLUSH preset.
- 5Let it run until slushy, about 36 minutes.
- 6Dispense and garnish with a lime wheel.
Tips
- Pour the liquid mixture directly into the Slushi bowl and let the machine do the work for 20-60 minutes; don't try to rush it by pre-freezing.
- Check the consistency after 30 minutes by opening the lid, then give it another 10-15 minutes if it's still pourable rather than slushy.
- Use a sturdy spoon or the included scoop to serve, as the slush can be dense and packed down from the continuous churning.
Variations
- Swap the watermelon hard seltzer for another fruit hard seltzer like strawberry or pineapple, keeping the vodka and watermelon juice amounts the same.
- Replace the watermelon juice with fresh lime juice concentrate or lemonade concentrate for a different fruit profile while keeping the seltzer and vodka.
FAQ
- Can I use regular seltzer instead of hard seltzer?
- Yes, but increase the vodka by 1-2 ounces to maintain the flavor and alcohol content, then pour the base into the machine as usual.
- What do I do if the slush won't freeze after 45 minutes?
- Make sure your Slushi bowl was fully frozen before use and that you poured all ingredients in at room temperature; if the machine runs but nothing freezes, the bowl may have thawed or lost its chill.
- Can I make this without vodka or with less alcohol?
- Yes, you can omit the vodka entirely or use half the amount; just note that less alcohol may freeze slightly faster since there's less liquid to churn.
- How long can I keep the finished slush in the machine?
- The Slushi keeps the slush cold for about 30-45 minutes after it's done churning, but it will gradually melt if left sitting; serve and enjoy it fresh for best texture.
Nutrition
Per serving · makes about 4 servings · estimated
Ratings & Reviews
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Meet Marty Cole
I'm a home cook who got a little obsessed with the Ninja Slushi and Creami. I test every recipe in my own kitchen on a real machine, dial in the texture, and only post the ones my family actually finishes.
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