Ground cherries (Physalis pruinosa) are an appealing fruit for the home gardener, offering a unique sweet-tart flavor often described as a mix of pineapple, vanilla, and tomato. This annual plant, a relative of the tomato and tomatillo within the nightshade family, produces small, golden berries encased in a papery husk. Growing them from seed provides the earliest harvest, allowing you to enjoy a steady supply of this distinctive fruit throughout the late summer and fall. The process is straightforward, but it requires attention to warmth and timing to ensure a successful start to the season.
Starting Ground Cherry Seeds Indoors
Starting ground cherry seeds indoors is necessary to give the plants a head start in regions with shorter growing seasons, as they require a long period to mature and fruit. Sow seeds six to eight weeks before your area’s average last expected frost date. Ground cherry seeds require significant warmth to germinate, with an optimal soil temperature range between 75° and 85°F.
Use a seed starting mix in small containers or seed cells. A heat mat placed beneath the trays will maintain the necessary soil temperature. Sow the seeds shallowly, about one-quarter inch deep, and keep the starting mix consistently moist but not waterlogged. Germination often occurs within one to three weeks under warm conditions.
As soon as seedlings emerge, they must receive strong light to prevent them from becoming weak and leggy. A dedicated grow light is usually better than a sunny windowsill. Once the seedlings develop their first set of true leaves, begin feeding them a diluted organic liquid fertilizer about once or twice a week.
Hardening Off and Transplanting Outdoors
Before moving seedlings outdoors, they must undergo “hardening off” to acclimate them to the environment. This transition prevents transplant shock from sudden exposure to sun, wind, and fluctuating temperatures. Begin the process one to two weeks before the final transplant date, which should only happen once all danger of frost has passed and night temperatures remain above 50°F.
Start by placing the seedlings in a shaded, sheltered outdoor location for one to two hours daily, bringing them back inside each evening. Over the course of the week, progressively increase their time outdoors and gradually introduce them to direct sunlight. This slow exposure strengthens the stems and prepares the plant for the garden.
When transplanting, choose a sunny spot that receives at least six to eight hours of direct sun daily. Ground cherries thrive in well-draining soil with a pH ideally between 6.0 and 6.8. Space the sprawling plants two to three feet apart to ensure good air circulation and prevent disease.
Essential Care and Maintenance
Once established, ground cherry plants require consistent moisture, especially during flowering and fruiting, but they do not tolerate soggy conditions. Water deeply and infrequently, aiming for about one inch of water per week. Applying a two-inch layer of organic mulch, such as straw, around the base of the plant helps suppress weeds and retain moisture.
Ground cherries prefer less nitrogen than tomatoes, as too much nitrogen leads to excessive foliage growth instead of fruit production. A single application of a balanced organic fertilizer worked into the soil at transplanting is often sufficient for the season. Light side-dressings can be applied mid-season if the plants appear to be struggling.
Due to their low, sprawling growth habit, support is beneficial to keep the fruit off the soil and improve plant health. A small tomato cage or stakes can contain the branches and prevent fruit from rotting or becoming a target for pests. Common pests like flea beetles and tomato hornworms may target the plants; a floating row cover prevents flea beetle damage, while hornworms can be removed by hand.
Harvesting and Storage
The unique indication of ground cherry ripeness is that the fruit naturally drops to the ground. The papery husk (calyx) surrounding the berry turns from green to a dry, tan, or straw color as the fruit matures. The berry inside turns golden-yellow or orange, and the fruit is only edible once fully ripened.
Harvest the fruit from the ground frequently, as leaving them there can encourage pests or cause splitting and self-seeding. Some gardeners lay down a clean ground cover or plastic to simplify the collection of fallen husks. If the husk feels light and dry, the fruit inside is ripe and ready.
Ground cherries have an excellent storage life, provided the protective husk is left intact. Stored in their husks in a well-ventilated container, they keep at cool room temperature for one to two weeks. For longer storage, they can be kept in a cool, dark place with good air circulation for up to three months.