Pick the flowers. Choose fully open, bright yellow dandelions from a clean area away from roads, pesticides, and pet zones. Pick on a dry day if possible.
Separate the petals. Pull or trim off the yellow petals and discard the green parts, which can make the syrup bitter. This step takes a bit of time but makes a big difference.
Rinse lightly. Give the petals a quick rinse in a colander to remove dust or tiny insects.
Don’t soak them too long or you’ll wash away flavor.
Make a petal tea. Add the petals and 4 cups of water to a pot. Bring to a gentle simmer, then turn off the heat. Add lemon zest and a few slices of lemon.
Cover and let steep for 30–60 minutes. For a stronger flavor, you can steep up to 4 hours or refrigerate overnight.
Strain well. Pour the mixture through a fine strainer or cheesecloth into a clean pot. Squeeze the petals gently to get all the liquid.
Discard the solids.
Add sugar and lemon. Stir in 3–4 cups of sugar and the juice of the lemon. Start with 3 cups; you can add more if you want it thicker and sweeter. If using vanilla or ginger, add it now.
Simmer to desired thickness. Bring to a gentle simmer over medium-low heat.
Stir often to prevent scorching. Cook 25–40 minutes until it thickens to a syrup. Remember, it will thicken more as it cools.
Check consistency. Drop a little syrup on a cold plate.
If it slowly forms a bead and doesn’t run all over, it’s ready. If it’s too thin, simmer a bit longer; too thick, stir in a splash of hot water.
Remove flavor add-ins. If you added vanilla bean or ginger pieces, take them out.
Jar and cool. Pour the hot syrup into clean jars. Let cool to room temperature, then seal and refrigerate.