Final report for FNE24-104
Project Information
Low temperatures in the fall and early spring have a negative impact on fig growth, yield, and production. We investigated the increase in fig yield under high tunnels in the cold environment of Maryland's Zone 7A. We have 40 one-year-old fig trees planted within the high tunnel and 10 fig trees planted outside the high tunnel. This germplasm is local with unknown varieties; therefore, this work helped in selection and conservation of local germplasm. We measured and recorded temperatures in several spots within the high tunnel in the first year. We tracked the waking hours of the fig trees inside and outside the high tunnel to compare production and ripening times. In first year, the figs planted within the high tunnel yielded five times more and ripen several months earlier.
In the winter, we used water barrels, woodchips to add passive heat to the tunnel. we monitored the temperature and found that the temperature in the tunnel dropped to outside temperature at night. Figs branches didn't survive the winter. However, we noted that a few branches that were buried underneath the woodchips survived (which we thought they would die as fresh woodchips kill plants usually). The figs had huge growth as although the branches died the roots were still strong and we realized that the distance between them should be much farther.
In the 2nd year, although we used woodchips, the weeds grew out of the weeds layer and was hard to kill. We grew sweet patatoes to suppress the weed and retain the water. where sweet patatoes vines covered, there were less weed.
With the death of the branches, we didn't have figs until much later in the season, compared to the first year. However, we noted fig rip until much later in the season compared to the outdoors one.
We had high school students designed a watering system. It turned out we don't need much water for the Fig. Automatic system is not necessary. we also hosted a three batches of visitors to show our fig growth under the high tunnel.
In summary, we learned about all the species we grew, how to preserve the branches through winter, and that the yields are much higher compared to outside. We need to constantly remove the extra branches. At most 4 branches are necessary. The distance between the trees should be around 8ft. Woodchips are excellent passive heat that can help preserve the fig branches.
The main objective of this study is to evaluate the yield potential and season extension capabilities of figs in Maryland's 7A zone. The project will put high tunnels to the test, along with naturally easy overwintering methods and specific trimming procedures. The ultimate goal is to provide vital information that will help local farmers maximize revenues by selling fresh, locally farmed figs, thereby contributing to the community's economic development. Furthermore, identifying locally available unknown fig germplasm at our farm aids in the conservation of fig biodiversity in our region.
Fig is a subtropical plant that can resist temperatures well below freezing (about -10°C), making it suitable for USDA Cold Hardiness Zone 8 and above. In contrast, Maryland is in USDA Cold Hardiness Zone 7, making fig production problematic and challenging. During harsh winters, fig trees die back to the ground. Surviving roots develop several stems the next spring and summer. Because of this annual stem and branch rejuvenation, fruit growth and ripening time have been decreased. Because figs do not ripen on the plant, it is necessary to lengthen the growing and harvest season in Maryland. Following approaches have been used to successfully overwinter fig trees (Lee, 2021).
- Growing in containers and moving them inside in winter.
- Planting in the ground each spring and digging up each year.
- Wrapping the stems of the outdoor-planted fig to protect from harsh winter cold.
- Laying down or burying stems.
- In-ground cultivation in a cool or unheated greenhouse or hoop house.
The first four methods are time-consuming and labor-intensive, making them appropriate for small-scale home gardening but inefficient for large-scale commercial cultivation. To address these issues in fig production, we intend to use a high tunnel to extend the growing season. During the harsh winter, the high tunnel provides single-layer protection by collecting solar radiation and deflecting frigid winds. As seen this year, the temperature within the tunnel is higher than outside, stimulating early shoot growth in spring and rapid fig development in summer. In Maryland, figs normally ripen in October, with the first average frost day occurring around October 15. Within the tunnel, however, the ripe time may advance to September, and the additional protection in the fall can avoid early frost damage, extending the harvest season to early November. High tunnels may serve an important role in fig production in the USDA Cold Hardy Zone 7A of Maryland, providing a regulated microclimate that mitigates the obstacles of frost and low temperatures (Tom, 2022). These structures extend the growing season, allowing figs to thrive outside of their natural range. This season extension is critical for increasing yields and guaranteeing consistent fruit output, which helps to ensure local food security. High tunnels not only protect against harsh weather, but they also create a favorable environment for figs, boosting sustainable agriculture methods in colder regions and supporting the region's economic sustainability of fig production. We intend to evaluate the use of water barrels, hay bales, wood chips, and other similar materials to give passive heat to the tunnel. These natural materials aim to improve overwintering success rates by providing additional protection and balancing temperature fluctuations. The presence of passive heat in high tunnels improves sustainability by minimizing reliance on external energy sources. Utilizing solar heat supports environmentally friendly agricultural methods while reducing carbon emissions. Longer growing seasons boost production, promoting local food resiliency. This environmentally friendly technique ensures the long-term viability of both crops and ecosystems. Inside the greenhouse, figs may grow rapidly and create numerous new shoots, potentially reducing yield. To overcome this, we aim to use a fig tree pruning strategy that involves training the figs as espaliers (plants trained into two-dimensional patterns). This method simplifies future pruning, enables more light on the branches, and requires only 2-4 major branches to be kept close to the ground. Additional protection measures will include placing hay bales on both sides of the branches and covering them with row covers during extreme cold conditions. Local unidentified fig germplasm is also accessible at our farm and will be evaluated for yield and climatic adaptations in the current study. Conserving unknown native fig germplasm is critical for biodiversity conservation and sustainable agriculture. We can unlock potential benefits such as disease resistance and adaption to local climates by preserving these distinct genetic resources. Conservation initiatives help to maintain a resilient and diverse agricultural landscape, which promotes food security for future generations. In addition, five new varieties will be tested in the current study. These varieties will be chosen based on the advice of fig specialists/technical advisor, who believe these varieties will perform better in USDA Cold Hardy Zone 7A.
We have 50 sheep, about 100 ducks and 100 chickens on the farm. We hope to build a purmaculture orchard. WE hope to use chicken tractor and integrate sheep with the orchard for grass growth control.
Cooperators
- - Technical Advisor
Research
There are four different variety We are recording the different growth and fruiting behavior, including the leaves shapes, fruit size, color and yield. One of the varieties is big, light green color, with yellowish flesh, it is very sweet once they fully mature, but it has very thin skin and very easy get bruise, also the ants are very easy to go into the center through the big holes. The most early and product fig have purple skin and red flesh, it matured very early and have a very long harvest period. Another variety is media size with green firm skin and red flesh, very good for commercial use. The last variety has small purple fruits, but it takes long time to mature, and the taste are not very good either.
We recorded the amount of the fig harvest during the harvest season as a referral for next year yield.
We put about 3 inches compost under each tree in springtime to provide the nutrients during the growth season. We also did the soil test at the beginning of the growing season to get the baseline of the soil situation.
We installed the smart irrigation system; it automatically waters the fig trees during the hot summer months and save us time and efforts.
We also installed the automatic temperature recording sensor which provide us the consistent temperature data.
High Tunnel, Infrastructure, and Plant Varieties: The central structure of our project is the 34ft x 72ft high tunnel. Within the high tunnel, 40 one-year-old fig trees are planted, while 10 additional one-year-old fig trees are positioned outside. These trees represent unknown local fig germplasm. This germplasm was screened for yield and season extension under high tunnel and outside conditions (10 fig trees are planted outside). We tracked growth trends, fruiting behavior (time of fruit development from flower to fruit harvest), fruit color, fruit yield (fruit yield (lbs) per plant throughout the harvesting season), pest and pathogen resistance (by monitoring canopy biweekly for pest and pathogen infestation), and adaptability to local conditions (effect of high and low temperature on yield and fruit behavior). This information was used to label different species. Miaochan Zhi has been collecting this germplasm for the past ten years. Data was gathered on both recognized and unidentified fig varieties under high tunnel and outside conditions. Because the number of trees for a particular variety is undetermined, data was collected on available trees for identified variety or unknown type. The number of trees for each identified and unknown germplasm were recorded. Pictographic data on tree morphology, fruit shape and color, and inner mass for each identified variety or unknown type were collected. Season extension was also evaluated for each fig variety by documenting first and last harvest of the season under high tunnel and outside conditions. We visited the farm of our technical advisor Threefold Farm and identified one species that is best to grow inside the high tunnel. We purchased 20 branches and has started to grow them inside the high tunnel to compare with our different variety. For those that are not doing well within the high tunnel, they were removed. We only kept those that fruit well.
In high tunnel and outdoor conditions, five 1-year old trees of each type were planted. Five trees were studied for growth trends, fruiting behavior/development time, fruit color, fruit yield, pest and pathogen resistance, and adaptability to local conditions. Season extension was evaluated for each fig variety by documenting first and last harvest of the season under high tunnel and outside conditions. These plants was purchased from a commercial nursery using Miaochan Zhi's personal finances, as perennial tree purchases are not permitted under this award. Fruit yield was determined per plant.
Soil Preparation and Installation of Temperature Sensor and Irrigation System: In the spring of the first year (2024), we concentrated on preparing the soil and installing the irrigation system within and outside the high tunnel. This included conducting soil tests to assess soil conditions and purchasing compost or fertilizer based on the results of the testing. Furthermore, we installed a comprehensive system that includes temperature measurement equipment as well as a record-keeping mechanism for both inside and outside the high tunnel.
Pruning Technique: The 40 one-year-old fig trees was heavily pruned and trained by picking a robust main stem or "trunk" and trimming off the tip, leaving roughly 18 inches in height. Two branches was trained along a temporarily installed horizontal bamboo cane, either opposite each other or perpendicular to the trunk, making what we call "cordons."
As most of the branches were dead after first year, we have about 6 branches that were successfully trained to be parallel to the ground and new shoots did grow on each one vertically, as expected. Vertical shoots grown in the previous season was cut down to the cordon from which they originated. Additionally, any root sprouts or shoots developing along the trunk was trimmed to maintain the desired structure.
Harvest: We meticulously recorded fruit appearance times (fruit behavior), the location of fruit on the shoots, ripening durations, and observed the growth variations inside and outside the high tunnel among different fig varieties. As autumn approaches, we pruned tips and unripe fruit to accelerate fruit ripening. Harvest times was recorded, and the fig trees' ability to withstand frost was compared inside and outside the high tunnel. We also documented the timing of leaf fall for both environments.
Passive Heat in High Tunnel: To protect fig trees during extreme cold days, we used a row of large water barrels filled with water and placed them on the northern side of the high tunnel. These water barrels absorbed excess heat during sunny days and gradually released it during colder periods, helping regulate temperature changes inside the tunnel. We added one foot of woodchips in November to keep the ground from freezing.
Irrigation: We only water the figs during the high heat of the summer. We noted that Figs doesn't need much water and can survive the whole winter without watering.
Data analysis: Economic data was collected based on yield per plant. Data was collected on 5 plants each for each variety . However, for unknown and identified germplasm data was based on number of available plants of each type. We also compared the yield for inside and outside figs that is of same variety.
The outlined management plan was repeated in the second year. However, as most of the branches dead, the second year data was limited. In the fall of 2025, we added additional water barrels and more woodchips. At the time of reporting, most of the branches survived the winter.
Annual report 12/2/24
We observed the growing condition during the spring, summer and fall. Numbering each tree, recording the status of the tree including how may new branches, old branches and the 2nd shoots from the old branches. These trees are very vagarious, it is very important to keep checking the suckers from the base, side shoots we don't want and pruning them, we also pruned the tips in Augst to make sure to put all the energy to mature the fruit. During the Aug-Nov. we recorded all the fig harvest and analysis the results with the branches for each tree.
We observed the growing condition during the spring, summer and fall. Numbering each tree, recording the status of the tree including how may new branches, old branches and the 2nd shoots from the old branches. These trees are very vagarious, it is very important to keep checking the suckers from the base, side shoots we don't want and pruning them, we also pruned the tips in Augst to make sure to put all the energy to mature the fruit. During the Aug-Nov. we recorded all the fig harvest and analysis the results with the branches for each tree.
Annual Report 2025
In December we added water barrel filled with water to regulate the temperature change inside the tunnel. We put all branches down and held it down with metal pin, water barrels and cloth made rope.
We checked the temperature; the inside temperature still goes to temperature as low as the outside and became very high around noon.
In spring, most of the branches dead except those that were accidentally buried underneath the woodchips.
The fig grew slowly and didn’t fruit until very late. We started to harvest around September 2025.
For winter 2025, instead of just bending down the branches to close to the ground, we bury them under the woodchips.
For the few that survived 2024 winter and 2025 spring, they have formed the growth we wanted, as shown below.
We will keep doing it this year.
Also, we noted as the figs grow we need to constantly prune the extra branches. And we have way too many trees under the high tunnel. We will thin out half of the trees planted as we would like to promote horizontal growth as shown above.
We noted that Figs grow underneath high tunnel has much higher yield than those outside without production
1. they start the growth early in spring
2. much vigorous growth
3. fruit early
4. bearing fruit all the way to Oct.
we noted that winter protection is necessary. Figs need to be buried underneath the woodchips. passive heat created by water barrels is not sufficient. In addition, we noted that Figs branches don't go rotten underneath the woodchips.
we noted that Figs need constant pruning and fruit needs immediate pick. We noted that it is best just to keep 2 or three branches. More branches will result in no fruit.
We also noted that different species behave significantly different under high tunnel.
Education & outreach activities and participation summary
Participation summary:
We visited threefold farm to learn and communicate the fig growing skill.
We didn’t host a large party. We shared the fig under high tunnel with two groups of visitors. We will also share in the upcoming local farm conference---2026 Future harvest annual conference, Chesapeake Alliance for sustainable Agriculture.
Learning Outcomes
Don't plant too close to each other. 10 ft is a good separation distance.
One type of fig that has green skin and purple fruit is doing really well.
we built an irrigation system.
we realized that the temperature vary in huge range (go very high at afternoon and go very low close to outside temperature at night) compared to outside temperature change.
Fig doesn't require much water
Fig needs constant pruning. 2 branches are sufficent
They produce much more than outdoors one.
Project Outcomes
a neighboring farmer Kelly Hensing who has reached out to me saying she hope to get Figs for the farmer's market. it is in huge demand.
I have three patches of visitors. they all love the figs. we harvested a lot. I showed them the figs inside and outside so they can see the difference in growth.
everyone loves fresh figs. They are happy to see that I can grow them successfully and harvest so much by using a high tunnel.
I did use wood chips and water barrels to regulate the temperature.
Tree companies are happy to provide tons of woodchips for me.
I learned that sweet patatos are a great companion plant that suppress the weeds underneath. I harvested a lot of sweet patatoes in winter after figs leaves are all gone.
2026 I expected to bring this our local farmer's market. It is in huge demand.
During the harsh winter weather we may need additional heat. In spring the fig started to grow then a late frost kills them all. Regardless, they grow much sooner than outside ones.
Weeds control is super important. I tried woodchips, black plasitic, digging, Sweet patatos vines turned out to be really good one.
I will help other farms growing figs by providing fig cuttings of many different varieties I preserved through this project.
I will take half of the figs outside as it was too crowded. The growth inside is much vigorous than outside. more space is needed.