The Fascinating World of Physalis: Growing Goldenberries and Ground Cherries

By Michael Brown

Goldenberries
Goldenberries are a relative of tomatillos.

Are you a farmer searching for a unique and enticing crop to captivate your customers and increase sales? Look no further than the intriguing world of Physalis. Physalis is a genus of flowering plants in the nightshade family, and it includes the popular tomatillo. These plants, which are distantly related to peppers, tomatoes, and potatoes, grow primarily in warm temperate and subtropical regions, particularly in the Americas. One of the most distinguishing features of this genus is the thin, paper-like husk that encloses the fruit. Ground cherries, which you may already be familiar with, are a common example of Physalis fruit.

Ground cherries, scientifically known as Physalis pruinosa, have been a hit among customers at the NB Community Harvest Garden in New Brunswick, Canada. Parents often send their children to forage for these fruits due to their low-growing nature and tendency to easily fall from the plant. However, despite their popularity, harvesting ground cherries can be quite challenging. Typically grown in small quantities, you can find these attractive fruits at farmers markets or as part of a CSA share. Occasionally, you may even come across ground cherries from South America in larger supermarkets.

On the other hand, the goldenberry, or Physalis peruviana, which is the larger sibling of the ground cherry, is less commonly cultivated. Growers face difficulties due to the lack of reliable information on optimal cultivation methods, confusion regarding suitable cultivars, and limited sources of high-quality seeds. However, a breakthrough may be on the horizon.

Located just a short drive from Rutgers University in New Brunswick, New Jersey, HortFarm 3 is home to various fruit, nut, and vegetable trials. These trials aim to expand the options available to New Jersey farmers and discover the best practices for growing different crops. Among the trials, the largest planting of goldenberry on the East Coast can be found on two acres of this vast farm.

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Dr. Ed Durner, a professor at Rutgers, has been studying goldenberry for several years. His goal is to identify promising strains and develop production guidelines to support farmers interested in exploring this delicious and nutritious fruit. Dr. Durner has recently received a grant to introduce goldenberries to farmers with CSAs and farmers markets in the Northeast.

When delving deeper into the world of ground cherries and goldenberries, one quickly realizes the confusion surrounding the two main species: Physalis pruinosa and Physalis peruviana. Consequently, understanding the available options and using correct nomenclature becomes crucial.

For clarity, let’s refer to these fruits using their Latin names. Ground cherries, or Physalis pruinosa, are prostrate and spreading plants that bear small, approximately ½-inch fruits. These fruits easily fall from the plant when they ripen. On the other hand, goldenberries, or Physalis peruviana, grow as large, upright plants, reaching heights of 4-6 feet. The fruits of goldenberries are about ¾-inch in size and need to be pulled or cut off the plant when ripe.

Now, let’s explore the basics of growing these fascinating fruits.

Germination

To start the germination process, lightly cover the seeds with suitable soil or planting medium. The optimal temperature for germination is around 85 degrees Fahrenheit, although a range of 75-90 degrees Fahrenheit is also acceptable. Germination may be significantly delayed if temperatures drop below 65 degrees or exceed 95 degrees Fahrenheit. Seeds should sprout within 2-6 weeks. It is advisable to start seeds early, around the same time as peppers or tomatoes, and transplant them outdoors after the temperature warms up.

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Growing

Since Physalis is native to South America, it is treated as an annual in temperate regions, similar to tomatoes or peppers. While seedlings can tolerate light frost, temperatures below 30 degrees Fahrenheit will damage them. For optimal production, it is best to grow Physalis on well-drained, “poor” soils. These plants require consistent irrigation, as they are not drought-tolerant. Therefore, both Physalis pruinosa and Physalis peruviana may not be suitable for dry field cultivation. To ensure proper development and ripening of the fruit, it is essential to provide them with approximately one inch of water per week.

Fruits are ready for harvest when they turn a golden color, which can usually be seen through the husk. The husk itself will appear yellowish-brown and translucent when the fruit is ripe. Once harvested, the fruit will not continue to ripen. Therefore, it is important to pick fully ripe fruit. Make sure to pick fruit when it is dry, as moist fruit is prone to mold. If left in the husk, the fruit will keep for up to three months at room temperature. Good air circulation is also beneficial in preventing mold growth, removing the pressure to sell fruit immediately before it spoils.

Ground cherries (P. pruinosa) typically start to bear fruit approximately 75 days after transplanting, while goldenberries (P. peruviana) require a longer season of about 120 days. Therefore, if you are cultivating goldenberries in New Jersey (zone 6b), starting the plants indoors in late March will result in fruit production around the end of August.

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Pests

The most significant pest that affects Physalis plants is the 3-lined lema beetle, also known as the 3-striped potato beetle (Lema trilineata). In some instances, hornworms (Manduca species) have also been identified as pests on certain P. peruviana plants.

Pros and Cons

P. peruviana, or goldenberry, requires a longer growing season before the fruits are ready for harvest. Additionally, the fruit production can be moderate, and reliable sources of seeds are limited. However, Dr. Durner is actively addressing some of these issues through his ongoing trials. One advantage of growing goldenberries is that the plants are larger and more upright. The fruit does not abscise (fall off naturally) when ripe, which offers more control and easier harvesting conditions, eliminating the need for stooping. However, this also means that the fruits must be cut off the plant, making the harvest process more time-consuming.

On the other hand, ground cherries (P. pruinosa) offer a longer harvest window and appear to be more productive than goldenberries. There is also a wide variety of seed sources available, although specific differences between varieties are not extensively documented. The main disadvantage of P. pruinosa is its low, sprawling habit, which makes harvesting challenging.

Enter the fascinating world of Physalis and explore the many possibilities of growing goldenberries and ground cherries. Mike Brown, the owner of Pitspone Farm, a small-acreage berry farm and nursery in central New Jersey, shares his insights in this article.

This story first appeared in the August 2019 issue of Acres U.S.A. magazine.


For more information on goldenberries and ground cherries, visit the Ames Farm Center.