Equipment
Large pot (15- 19 Liters or16–20 quart)
Water bath canner
Food processer or Blender
Food mill or jelly strainer
Large spoon or ladle
Canning funnel
Jar lifter
Lid lifter
Half-pint canning jars with lids and rings
Fine sieve or cheesecloth
Dishwasher or boiling water for jar sterilization
Ingredients
Watermelon, seedless & rind removed (chopped): ~600 g (4 cups)
Must be a true 4 cups “liquid and all,” no air gaps per the source.
Sugar: 700 g (3½ cups) granulated
Lemon juice: 240 ml (1 cup)
No-sugar-needed powdered pectin: 1.5 packages
Preparation
1) Select ripe watermelon
Choose sweet, ripe, not mushy/overripe watermelon. Any flesh colour works.
2) Wash, cut, and dice
Wash the rind, then cut open and scoop out flesh. Dice into ~2.5 cm (1 inch) chunks and save all juice (work in a tray to catch it).
Measure 4 cups chopped watermelon (with liquid).
3) Purée
Blend until smooth.
Source note: it says the 4 cups chopped “should reduce to ~2 cups purée,” and then says 2 cups purée is what you need.
Pour purée into a large pot.
4) Add lemon juice
Add 1 cup (240 ml) lemon juice. Do not skip.
Optional (if you want a clearer jelly): strain now through cheesecloth/strainer.
5) Pre-mix pectin with a little sugar
In a small bowl, mix pectin with ¼ cup sugar (taken from the 3½ cups total). This helps prevent clumping.
6) Cook purée + pectin to a full boil
Stir pectin mixture into the watermelon purée. Cook over medium-high, stirring, until a full rolling boil (can’t be stirred down), ~5–10 minutes.
7) Add remaining sugar; boil hard 1 minute
Add the remaining sugar (3½ cups minus the ¼ cup you used). Return to a full rolling boil and boil hard for 1 minute, stirring constantly.
8) Test the set (optional)
Cold spoon test. If too loose, add ¼–½ pack more pectin, boil 1 minute, retest.
9) Fill jars
Fill hot jars to ½ inch (1.25 cm) headspace. Wipe rims, apply lids and rings fingertip-tight.
10) Process in boiling water bath
Process with jars covered by at least 2 inches (5 cm) water.
Process time: 10 minutes (source’s “general” guidance)
Altitude adjustments weren’t provided specifically for this recipe—see “Issues.”
11) Cool and check seals
Cool 12–24 hours, check seals.