The ground cherry (Physalis pruinosa) is a unique, nightshade-family fruit encased in a distinctive papery husk, similar to the tomatillo. The ripe fruit is typically golden-yellow with a sweet-tart flavor, often described as a blend of pineapple, vanilla, and citrus notes. Unlike its upright relatives, the ground cherry plant has a low, sprawling, and bushy growth habit, which is an important consideration for garden layout.
Starting Ground Cherries Indoors and Transplanting
Ground cherries require a lengthy growing period and are sensitive to cold, necessitating an early start indoors to ensure a full harvest before autumn frost. Seeds should be sown six to eight weeks before the last expected spring frost date. For successful germination, the seeds require a warm environment, ideally maintaining a soil temperature between 70°F and 85°F.
Providing bottom heat with a seedling heat mat helps achieve consistent warmth, speeding up germination. Once seedlings emerge, they need bright, direct light (such as from a grow light) to prevent them from stretching and becoming weak. As the last frost date approaches, the young plants must undergo “hardening off,” gradually exposing them to outdoor wind and direct sunlight over seven to ten days.
The outdoor planting site should receive full sun (at least six hours of direct light daily) and have well-draining soil amended with organic matter. Transplanting should only occur once all danger of frost is past and the soil temperature has warmed to at least 70°F. Due to the plant’s wide, branching nature, space plants two to three feet apart to allow for proper air circulation and growth.
Essential Care: Water, Nutrients, and Support
Consistent moisture is necessary for ground cherry plants, especially once they begin to flower and set fruit, requiring about one inch of water per week. While established plants can tolerate some drought, inconsistent watering can cause flowers to drop prematurely, reducing yield. Applying mulch around the plants helps maintain soil moisture and keeps the sprawling fruit clean as it matures.
Ground cherries belong to the same family as tomatoes; they thrive in nutrient-rich soil but do not require excessive nitrogen. Too much nitrogen results in overly large, bushy plants that produce very little fruit. Incorporate compost into the planting site and use a balanced, continuous-release fertilizer sparingly, switching to a low-nitrogen formula once heavy fruiting begins.
Although the plants are naturally low-growing, their extensive branching habit benefits from physical support. Using a small tomato cage or staking system helps lift the branches and fruit off the ground. This technique protects the developing fruit from soil-borne diseases, improves air flow, and maximizes garden space.
Ground cherries are relatively hardy against disease but are susceptible to common garden pests, including flea beetles, tomato hornworms, and cutworms. Inspecting plants frequently allows for handpicking larger pests, while a targeted application of insecticidal soap or Bacillus thuringiensis (Bt) can manage smaller insects and larval stages. Maintaining healthy plants with adequate water and sunlight is the best defense against potential issues.
Knowing When to Harvest
The harvesting method for ground cherries is unique, as they should never be picked directly from the vine. Full maturity is signaled when the fruit naturally detaches and drops to the ground. This typically occurs when the protective husk (calyx) changes color from green to a dry, tan, or papery brown.
The fallen fruit should be collected promptly from the soil to prevent damage or the attraction of pests. Gardeners can gently shake the plant to encourage ripe, loosely attached fruit to fall, making collection easier. Once gathered, ground cherries can be stored unhusked in a cool, dry, and well-ventilated location, such as a mesh bag or shallow tray. Storing the fruit in its husk at room temperature allows it to remain fresh for up to two weeks, or longer if kept near 50°F.