How to Plant, Grow, and Save Seeds from Ground Cherries (Physalis spp.)
Physalis grisea – commonly known as ground cherry, dwarf cape gooseberry, and strawberry tomato – produces a small yellow edible berry surrounded by a papery husk. Ground cherries produce hundreds of fruit on each plant.
Sow ground cherry seeds indoors 6-8 weeks before the last frost. Plant seeds ¼” deep. Seeds will germinate in 7-10 days. When transplanting into the garden, space plants at least two feet apart. If you have grown ground cherries before, you may not even need to plant this crop again as ground cherries often volunteer in the garden.
Ground cherries have a sprawling growth habit similar to tomatillos. Be sure to give plants plenty of space in the garden. Ground cherries are not susceptible to many bacterial, fungal, or viral diseases. However, plants do occasionally suffer damage from flea beetles, whiteflies, ground cherry leaf beetles, and mites.
At maturity, the husks of fruits become dry and papery, and the fruits drop from the plants. Mature fruits should be collected from the ground after they have fallen.
Eating and Storing
Ground cherries can be eaten fresh, processed into jam, and baked into pies.
Compared to many fleshy fruits, ripe ground cherries have a long shelf life and can be held for several weeks, for both eating and seed saving.
Ground cherry is an annual crop. It will complete its full life cycle, including germination, reproduction, and death, in one growing season.
When saving seeds from ground cherries, separate varieties by 300-1,600 feet. You only need to plant one ground cherry plant in order to harvest viable seeds. To maintain a variety over many generations, save seeds from between 5-20 plants.
Given that an individual ground cherry fruit can contain more than 100 seeds, many gardeners stop harvesting for seed after gathering a few fruits from each plant in the population and simply continue to harvest only for consumption. It is easy to freeze husked whole ground cherry fruits.
Ground cherry seeds can be processed by blending the fruits with ample water in a food processor. Remove the husks before processing to simplify the decanting process. To decant the mixture, pour the blended fruits into a larger container, add more water, and agitate the watery mash until the seeds separate from the pulp. When the seeds have settled to the bottom of the container, the pulpy water can be poured off the top, leaving only the seeds. Keep decanting this mixture until most of the pulp and any immature seeds have been discarded. The viable seeds that remain should be transferred to a very fine strainer, rinsed under a stream of water, and placed on a screen or coffee filter to dry in a cool, well-ventilated area.
Because ground cherry fruits are soft, small batches can be efficiently hand-processed by removing husks, cutting fruits, and squeezing the pulp and seeds into a bowl. The mixture can be mashed by hand, and decanted and rinsed as described above.
When stored under cool, dark, and dry conditions, ground cherry seeds will remain viable for 4-6 years.