Chinese lantern plants (Physallis) have husks that resemble bright orange paper lanterns once dried. Inside each husk is a scarlet fruit, similar in texture but not color to its close relative, the tomatillo. The fleshy fruit surrounds the seeds within. Chinese lanterns are annual plants, so they must be replanted in the garden each year. They readily self-sow themselves, but saving some seed allows you to plant the lanterns exactly where you want them to grow each spring.
Pick the lanterns from the plant once the husks have dried completely and turned papery. Peel the husk away from the fruits.
Place the fruits in a blender. Add water until the fruits are covered. Place the lid on the blender, then process them on the pulse setting until they are pulverized.
Pour the pulverized fruit into a bowl. Add another 1 to 2 cups of water to the mixture and stir to combine.
Soak the seeds for two to three days, or until the pulp separates and floats to the top of the water. Pour the water and pulp off the top of the bowl. The viable seeds settle to the bottom.
Remove the remaining seeds from the bowl with a slotted spoon. Place them in a mesh sieve and rinse the remaining pulp from them under running water.
Spread the seeds out on a paper towel in a well-ventilated area. Dry them for seven days.
Store the seeds in an airtight container in a cool, dark place until you are ready to plant them in spring. Label the container with the type of seed and the year harvested.