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You’re Making Your Watermelon Syrup All Wrong

5 from 8 votes

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watermelon syrup in a jar with two whiskey watermelon sour cocktails
Watermelon Sour

Stop cooking your watermelon syrup! I’m here to tell you I have an easy, hands-off way to get the flavor of fresh watermelon into an infused fruit simple syrup that is bursting with the same juices you find in each bite of that perfect summer watermelon. If there is one thing you take away from my entire site about summer cocktails it’s this: stop cooking your summer fruit syrups.

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Why Cooked Watermelon is Yucky

Have you ever had cooked watermelon in anything? No? Me neither, and there’s a reason. It tastes NOTHING like fresh watermelon. The flavor is muddied – not fresh and bright, and it tastes like watermelon flavoring.

If you’ve had a watermelon-flavored candy, you know that flavor is nothing like true watermelon’s taste. And it’s awful, nothing I want in my drink.

The normal way to create a fruit simple syrup involves heat. Fruit and water are combined over low heat with sugar, simmered for a bit, then cooled and strained. It’s great for some fruits, like blackberries, lemons, limes, rhubarb, and apples.

But for fruits that burst when fresh like strawberries, peaches, and melons, creating the simple syrup without cooking is the best way to preserve that fresh flavor.

How to Make Cold Process Homemade Watermelon Syrup

Watermelon Syrup for Cocktails - A bowl of watermelon with a dusting of sugar

When I started to work with fruit-infused simple syrups I was disappointed in the strawberry and watermelon syrup recipes I found. All of them tasted like cooked fruit because I was, in fact, cooking the syrup as I made it. 

But then I thought about the sugared strawberries my grandma would serve with whipped topping. In the morning, she would slice up strawberries and pour a cup of sugar on them. She’d let it rest until dinner. When she pulled it out the strawberries were swimming in a fresh strawberry syrup that kept the flavor of fresh berries.

So I tried her method and realized that adding sugar to most fruits causes the expression of juice from them. Behind the scenes, sugar is hygroscopic – which means when put in contact with something it attracts water. Sprinkling sugar on fruit pulls the water out of the cells in the fruit, and once that juice is in the jar or bag, it creates a simple syrup.

Because this process is done without cooking, the heat doesn’t alter the flavor of the compounds that make up the aroma and taste of the fresh fruit, leaving you with a syrup very close in flavor to fresh fruit.

Watermelon Syrup for Cocktails - A jar ready to be strained next to a measuring cup with strainer.

The general process for a watermelon syrup recipe is the same as any other fruit. At home, I add 1 lb of fresh, cut fruit or berries to a zippered plastic bag or glass jar. I sprinkle 8 oz of sugar on top and muddle lightly to break down the fruit. Then I put it in the fridge overnight or for 24 hours. 

Watermelon Syrup for Cocktails - straining the syrup through a metal sieve into a measuring cup.

When you remove it from the fridge, it will be a bright, vibrant color, and most of the juice will be clear. I mix it up a bit to finish dissolving the sugar, then use a metal sieve to strain out the syrup. I put the syrup in clean glass jar and store it in the fridge. 

The resulting syrup is tastes bright and vibrant and preserves that fresh taste you get from a perfectly ripe berry or fruit.

Watermelon Syrup for Cocktails - strained out watermelon solids from simple syrup in a metal seive over a glass measuring cup

How Long Does Fruit Simple Syrup Last

Because we’re not cooking the fruit-infused simple syrup, it will last about 10 days, but see below for a tip to extend that time into the 2 to 4-week duration.

If the syrups develop mold on the surface, the lip or the lid of the jar, it’s time to make a new batch. Melon syrups will settle at the bottom of the container, so don’t think there’s a problem if your syrup gets a little cloudy as you agitate it.

You can also freeze the simple syrup if you make a large batch. If the sugar to juice ratio is closer to 1:1 it will likely freeze solid, but closer to 2:1 and you can use it immediately from the freezer.  

Tips and Tricks for this Watermelon Syrup Recipe

watermelon syrup in a jar with two whiskey watermelon sour cocktails

Here are a couple of simple tips to make your homemade watermelon syrup easier and more delicious:

  • Use only ripe watermelons. Don’t use over-ripe melons or melons with cracks in them. To pick a ripe watermelon, tap it. Those that are heavy for their size and sound hollow inside are ripe and ready to eat. For more info on picking a ripe watermelon, head here: https://www.watermelon.org/watermelon-101/facts-faqs/
  • Seedless watermelons work best here. While watermelon seeds aren’t harmful here, if any of them are cut or broken during the muddling process they’ll make the syrup taste just a tiny bit herbal or vegetal. Not a lot, just a small bit. Since you’ll be using it in small amounts it won’t make a big difference in the flavor profile of your cocktail, but it’s something to be aware of.
  • Add vodka to the simple syrup to help it last longer. Because it isn’t cooked, cold-process fruit simple syrups don’t last as long. Sometimes as short as 10 days. Adding a bit of vodka helps them stay fresh and potent. I usually add ¾ oz to a 12-16 oz batch of simple syrup.
  • Alter the ratio of sugar to fruit as needed. I generally start with 1 lb fruit to 8 oz sugar. I tweak the amount of sugar-based on the sweetness of the fruit and how much juice it expresses. Taste-testing is your best friend. 
  • Change the sugar you use. You can use brown sugar, raw sugar, cane sugar, and more. You can even muddle the fruit in honey, maple syrup, or agave nectar for the same effect.

Other Watermelon Cocktails You Might Enjoy

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Recommended Bar Tools

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You probably already have these, but you may need them, too:

watermelon syrup in a jar with two whiskey watermelon sour cocktails

No-Cook Watermelon Simple Syrup – The BEST watermelon syrup recipe for cocktails

Heather Wibbels
Use this no-cook, cold process watermelon syrup recipe to make a bright, flavorful and fresh-tasting syrup to punch up the flavors in all of your summer cocktails. It just a quick muddle and a night in the fridge to get you to the best fruit-infused simple syrup you have ever had.
5 from 8 votes
Course Drinks
Cuisine Bourbon Cocktail
Servings 12

Equipment

  • metal sieve
  • measuring cup
  • glass jar

Ingredients
  

  • 16 oz fresh, cubed watermelon
  • 8 oz sugar
  • ½ oz vodka optional – it keeps the syrup fresh much longer

Instructions
 

  • Combine watermelon and sugar in a jar or a zippered plastic bag.
  • Muddle them together a bit and put the bag or jar in the fridge.
  • After 12 to 24 hours, stir up the contents until all the sugar is dissolved.
  • Strain through a metal sieve.
  • Store the watermelon syrup in a clean glass jar in the fridge.
  • Optional: add ½ oz vodka to the simple syrup to help it last as long as 4 weeks.
Tried this recipe?Let us know how it was!
By on June 15th, 2021

About Heather Wibbels

Heather Wibbels is a whiskey enthusiast (Executive Bourbon Steward, no less) with a passion for cocktails. She loves researching and designing cocktails, drinking cocktails, and teaching cocktails. Mostly whiskey cocktails, given her Kentucky location

More posts by this author.

7 thoughts on “You’re Making Your Watermelon Syrup All Wrong”

  1. 5 stars
    This looks so delicious and perfect for cocktails. We love watermelon and this recipe is so easy! I can’t wait to make this!

    Reply
  2. 5 stars
    I’ve never made a watermelon syrup before, but I’m glad that now I know the right way to do it! Can’t wait to give this a try, I think some great summer cocktails are in my future 🙂

    Reply
  3. 5 stars
    Can’t believe this could be home-made! I am excited to give this a try with my family! They love this kind of drinks. Thank you!

    Reply
  4. 5 stars
    This is very informative! Watermelon is one of my favorite fruits and I love the detailed explanation you have given here. Thanks for sharing.

    Reply
  5. 5 stars
    So much cheaper than the Torani syrups used by bars, you can buy it online for only about $7 but shipping is no less than $10 so $17+

    Reply

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