Methods for improving quality and conditions of ground cherry production-part II

Project Overview

Project Type: Farmer
Funds awarded in 2016: $5,652.00
Projected End Date: 12/31/2017
Grant Recipient: Calliope Farm
Region: Northeast
State: Maryland
Project Leader:
Lisa Garfield
Calliope Farm

Annual Reports


  • Fruits: general small fruits


  • Crop Production: food product quality/safety
  • Farm Business Management: value added
  • Production Systems: general crop production

    Proposal summary:

    Calliope Farm is interested in continuing experiments begun in the summer of 2014 (SARE grant FNE15-828) using techniques to increase the viability of ground cherries as a fresh market and value-added crop, by improving harvesting conditions. A combination of grafting, pruning, and trellising will be employed to create a more upright habit that eases time and labor intensity, while a net trough will catch the fallen fruit to eliminate ground contact. Data on harvest times, quantities and quality will be collected and analyzed to determine the usefulness of methods. Results will be shared at a Twilight Tour at the Lower Eastern Shore Research and Education Center.

    Project objectives from proposal:

    Demand for organically grown fruits is very high at farmers markets, as well as among Community Supported Agriculture (CSA) members and chefs, but is often in short supply due to pest and disease pressure, especially in the hot and humid climate of the more southern Mid-Atlantic states. Ground cherries (Physalis pruinosa) offer an appealing combination of minimal pest and disease issues, long harvest window, great flavor-equally applicable to sweet or savory dishes, and nutrition: high in vitamins C and A, as well as potassium and fiber, that can help fill that niche. Calliope Farm has been very successful in marketing ground cherries, but have had difficulty meeting the high demand due to the labor of harvest. Ground cherries have a low and sprawling habit and the fruit falls off the plant when ripe, requiring harvesters to stay bent over, or on hands and knees for long periods, lifting branches to pick up thousands of tiny fruits. Contact with the ground, even on ground cover, or straw mulch often results in soiled or compromised quality of fruit, especially after rain, and poses a potential for health risk (according to GAP principles).
    Home gardeners have traditionally prized ground cherries for use in pies, jams, and sauces. They have potential in many value-added products, but efficiencies are needed to make it possible to grow enough fruit to use in applications beyond fresh sales. Through experimentation we hope to expand the possibilities for small farms interested in adding to their arsenal of offerings.
    Experimenting with methods to increase the efficiency of harvesting ground cherries could potentially improve profitability of the crop and decrease labor. Many farmers and laborers suffer from back and knee issues due to time spent bending and kneeling. Reduction in activities that require those body-stressing positions could improve quality of life for both farmers and employees. Many farmers I’ve spoken with have tried growing ground cherries once, and then dismissed them because of the labor intensity. If improvements can be made, they might become a more commercially viable crop that has wide appeal for both fresh sales, and value-added products. The minimal pest and disease pressure means fewer inputs and less environmental risk by reducing the need for even organically approved pest controls, which, though not deemed harmful for human consumption, are often harmful to beneficial insect population. Keeping the fruit from coming into contact with the ground could allay possible health risks to consumers, as the fruit is often consumed raw. Purchased materials can be re-used over several seasons which represents both cost efficiency and respect for resource conservation.

    I will continue to experiment with methods of pruning, trellising, and grafting ground cherry scion to tomatillo rootstock, in combination with a catchment system, to create a more upright habit for the plants, and eliminate fruit contact with the ground. The results of last year’s experiment using these methods (SARE grant FNE15-828) were promising, but I would like to see if it possible to improve on the delay in fruit yield by testing different plant start times.

    Using the same techniques as last year we will attempt to hasten higher yields, as compared to the control group, by starting plants earlier. Three groups of transplants will be started in two-week intervals, to see if larger plants that have already been pruned at least once, might improve early harvest quantities. In addition, I will attempt to complete the grafting portion of the experiment.

    Five, 3’ wide x100’ long, raised beds will be planted with Cossack Pineapple ground cherries, a variety that we have been growing for the last seven years, at 2’ spacing, on black ground cover with drip irrigation. One row, our control group, will be treated as we have previously, allowing branches and foliage to grow with no interference. Rows 2-4 will be planted with stakes driven every five feet, to support two plants between every set, and plants will be pruned throughout the season to create a more upright habit that can be supported by twine, using tomato clips.   Row two will have transplants that were started in the nursery six weeks earlier than plants for the control planting (Feb. 15). Row three will have transplants started in the nursery four weeks earlier than the control planting (Feb. 30). The fourth row will have transplants started 2 weeks earlier than the control planting (March 15). The fifth row will be planted, staked, and strung at the same spacing, but will contain Cossack pineapple ground cherries grafted to a root stock of Verde Puebla tomatillos. Tomatillos are in the same family as ground cherries, and already have a more upright habit, with branches emerging higher on the stem, potentially allowing for less pruning prior to trellising. Grafting tomatoes sometimes results in earlier fruiting. It is possible that this would address the delay in yield that we experienced in last year’s experiment. Though the primary objective is to take advantage of the more convenient growth habit of the tomatillo, it will be interesting to observe if other traits, like larger fruit size, or staying on the plant until ripe, will show up in the ground cherries.

    All experimental rows will have a netting system designed to catch the fruit before it hits the ground. 3.5’x100 insect netting will be secured beneath the canopy, with the edges pulled upwards and attached to cross pieces that have been attached to each stake to create a “T” shape. The netting will create a trough, above the ground, for the fruit to fall into, allowing harvesters to collect fruit more efficiently, and with minimized bending or kneeling.   This technique was very successful, and all of the materials (black ground cloth, t-posts, netting), except the twine, were purchased for last years project, and can be re-used.

    All plants will be started in the transplant house at Calliope Farm, using heat mats for germination. All grafting will be done at Calliope Farm using the healing chamber I built and tested as a part of last years experiment.

    Due to a build up of the population of three-striped potato beetles on my farm, which impacted yields last year, I would like to continue the growing portion of the experiment only at the LESREC (Lower Eastern Shore Research and Education Center) location this year.

    Myself, and one farmhand or intern will be tasked with recording all aspects of the ground cherry experiments, with one or both of us making weekly trips LESREC. A spreadsheet will be created to record the following data: Harvest start dates, time spent harvesting each individual row (on average, twice per week, July thru September), yields from each row, fruit quality, and weather, as well as miscellaneous observations. Harvesters will be asked for feedback to gather additional insight about the differences in labor between each set of plantings, and their preferences. Results will be compared with records from previous seasons to give a broader foundation for comparison.

    Year 1 - 2016

    February 15- start ground cherry transplants for pruned row 2. Lisa Garfield- 1 hr.

    February 30- start ground cherry transplants for pruned row 3. Start tomatillo transplants for rootstock. Lisa Garfield-2 hr.

    March 7- start ground cherry transplants for pruned row 4. start ground cherry transplants for scions. Lisa Garfield- 2hr

    April 15- graft ground cherry scions to tomatillo root stock. Lisa Garfield 8hrs
    March 30- start ground cherry transplants for control row 1-Lisa Garfield 1hr
    (week of) May 7-prepare beds LESREC- Lisa Garfield and farm-hand. 8hrs
    (week of) May 15- plant 5 beds of ground cherries (250 plants) at LESREC. -Lisa Garfield and farm-hand. 5hrs

    (week of) June 1- Add stakes for trellising and begin weekly monitoring and pruning of experimental rows at both locations, stringing as soon as plants have reached 1' height (bottom string 8" above ground). Lisa Garfield and farm-hand. 4hrs.
    July 1- or when plants set flowers, attach netting catchment system below the plant canopy. Lisa Garfield 5hrs.

    July 15-September 30-begin twice weekly harvest, weighing and monitoring fruit quality. Lisa Garfield and farm-hand – 12hrs/wk.

    August- Twilight tour at LESREC


    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.