Rinse the seeds and let them stand in a bowl of water to allow any old flower parts to float to the surface. Make sure you have no stalks remaining on your seeds before packing them into small clean glass jars.
Make a 4-5% brine by mixing a good 2 tsp salt into 250ml filtered water. Fill the jars with the brine, making sure the seeds are well covered. However, they will float to the surface so find a small glass pebble to keep them below the surface. Put the lid on the jar, remembering to release any pressure daily.
They only take 3-4 days to ferment. If you want to keep them through the winter, put them in your fridge (or any cool spot) as soon as you’ve made them and let them mature slowly, checking them every week.