Prepare jars and a water bath canner (if canning).

Use a sharp paring knife to peel off the outside of the lemon peel.  Just the yellow part, leaving the white pith behind, but saving it for the next step.  Slice the lemon zest/peel pieces into thin strips.

Juice the lemons, saving the seeds to the side, but keeping as much pulp as possible with the juice.  Dice the white pith from the lemons as well, but keep all the parts separate. 

Take the lemon seeds and diced up white pith and place them in 2 cups water in a jam pot.  Simmer on low heat for about 30 minutes.  (The volume will reduce dramatically, but be careful not to let it boil dry.  During the simmer, the water will thicken as it extracts pectin from the citrus seeds and pith. In the end, you should have roughly 1/2 cup thickened gel.) 

Remove pith and seeds with a slotted spoon, leaving just the roughly 1/2 cup pectin water in the jam pot.

Add in all the lemon juice, pulp, and zest strips.  At this point, all the lemon should have been incorporated into the recipe, but the seeds and pith do not remain in the final zucchini jam.  

Add in the sugar, minced ginger, and zucchini.  (If you'd like a milder jam, use less ginger or omit it altogether.)

Turn the heat up to high and boil rapidly for about 10 minutes until the mixture reaches gel stage (220 degrees F).   Test the mixture with a digital thermometer, or on a plate that's been chilled in the freezer.

Pour the finished zucchini marmalade into canning jars leaving 1/4 inch headspace. 

Cap with 2 part canning lids and either store in the refrigerator for immediate use, or process in a water bath canner for 10 minutes.