Cube your watermelon and refrigerate for at least two hours before blending—cold fruit blends smoother and prevents the mixture from warming during processing. I learned this the hard way after my first batch turned out grainy instead of velvety. The reason this matters is that cold fruit releases more juice naturally, which concentrates flavor without adding extra sugar.

Combine the chilled watermelon chunks, cold water, sugar, lemon juice, lime juice, lime zest, and chopped mint in a blender. Pulse on high for exactly 45 seconds, then stop and scrape down the sides. You want a completely smooth consistency with zero visible fruit fibers—cloudiness is fine, but graininess means you'll taste separation in every bite.

Pour the blended mixture through a fine mesh strainer into a large bowl, pressing gently with the back of a spoon to extract every drop of liquid. This step removes the fibrous pulp that would create an unpleasant grainy texture in your finished cozy watermelon popsicles homemade. I skip this when I'm rushing, and I regret it every time.

Whisk the agar-agar powder into 2 tablespoons of the strained mixture until completely dissolved, then pour this back into the main bowl along with the sea salt, honey, vanilla bean paste, and coconut water. Stir for 2 full minutes—this isn't a quick mix. The reason you stir this long is to ensure the agar-agar distributes evenly; uneven distribution means some popsicles freeze solid while others stay slightly soft.

Divide the mixture among popsicle molds, leaving about half an inch of space at the top because the mixture expands slightly as it freezes. Insert sticks when the mixture reaches soft-serve consistency, which takes about 90 minutes in a standard freezer. I've tried freezing all the way before inserting sticks, and they always tilt awkwardly.

Freeze for a minimum of 4 hours, though overnight is genuinely better—this gives the agar-agar time to set completely and develop that perfect firm-but-not-rock-hard texture. The wait feels impossible, but it's the difference between popsicles that snap cleanly and ones that bend like rubber.

Run the outside of each mold under warm water for 3 seconds to loosen, then pull the stick gently while wiggling slightly side to side. If you pull straight up without the warm water, the popsicle tears and sticks to the mold—trust me on this one.