Post by Fernando de la Torre, ACG horticulture intern for summer 2025.
As a PhD student in plant breeding and plant genetics at UW-Madison, my specialization has been in breeding intersectional hybrids of Vaccinium – which is the family of plants that contains blueberry, cranberry, and lingonberry, among others. For summer 2025, I wanted to combine my interests in public botanical gardens with my experience in cranberry culture and production. ACG Director Reba Luiken approved the idea of creating a miniature cranberry bog in the space behind the kitchen garden at ACG, and I accepted her invitation to join the horticulture team as an intern for the summer.
The original idea of growing cranberries at ACG came from Isaac Zaman (former ACG horticulturalist) in 2023. After attempting a planting in an acidic raised bed, the cranberry plants did not survive the winter. The following summer, one of my former lab mates (Becca Honeyball) had talked with Isaac about putting cranberry plants into a “natural bog” space behind the kitchen garden. Becca and Isaac spearheaded the effort that year, focusing on making sure the plants would be well-watered with a drip line to try and mimic a natural bog. However the execution in 2024 was also unsuccessful since the cranberry plants never established sufficiently, which led to death by exposure from the harsh winds in the winter. As an ACG intern in 2025, my goal was to improve on the effort by applying what I came to understand about cranberry cultivation in a production capacity.
At the suggestion of Robin Grigleski and his father Ed (cranberry growers in Tomah, WI), I reviewed the requirements for commercial marshes and adapted them to meet the form and artistry of ACG. As a plant breeding student with experience in cranberry, I knew that commercial marshes were dug into the ground (about 5-10 feet deep) and plants are grown at the bottom in river sand. The depth is not only important for flooding the marsh during cranberry harvest, but also for overwintering. Commercial cranberry marshes in central Wisconsin are flooded right before the first winter freeze. The top layer of the pooled water in the marsh freezes, protecting the planting from the winter winds and freezing temperatures; an unfrozen layer of water often remains near the bottom, which provides the vital source of oxygen that the plants need to survive. Growers will periodically drain the unfrozen water and refill with reoxygenated water throughout the winter. To recreate a miniature cranberry bog inspired by a production marsh, I had to dig out a lot of dirt…
When I reached the clay portion of the soil, I placed a 1-2 inch gravel layer above the clay to help with drainage. In commercial operations, marshes are engineered to pump enormous amounts of water in and out of the planting, so water drainage is critical to avoid root rot and other diseases. Therefore, when commercial beds are first dug out, a layer of gravel is placed over the clay that lines the bottom, to improve drainage and avoid direct contact of plants with clay. With this in mind, I dug our miniature bog 2-3 feet deep but with a low grade, so that excess water could drain and pool on one side. On top of the gravel layer, I placed a 1-2 inch layer of fine river sand to promote rooting after cranberry plants were installed. When I planted the cranberries, I did so in a 1-2 inch layer of peat moss above the river sand layer. Although peat moss is not used in commercial operations for planting, peat moss is an important source of nutrition in natural, acid bogs. With the watering schedules and nutritional supplementation being different at ACG than in commercial marshes, I used peat moss to retain water and provide some nutrition while the cranberry plants were establishing themselves. Finally, over the top of the peat moss, I placed another inch of river sand to promote rooting of new cranberry runners. The project was completed in mid June.
As of August 2025, the miniature cranberry bog is looking great! Runners have been emerging and rooting into the sand. I will be maintaining the bog as the summer rains continue and the fall approaches. The plants will need to be insulated from wind and freezing in the winter, so I will be covering them with a semi-permeable canvas over the plants, in case snow does not accumulate. Overall, I am happy with the result. Once the cranberry plants experience one overwintering cycle in 2025, they will flower and set fruit in time for the ACG Harvest Festival in 2026. This miniature bog will bring the production of cranberries closer to students at UW-Madison and the ACG community.
As a plant breeding PhD student, one of my interests is breeding fruits and vegetables that not only have low management requirements but that also have ornamental value. With the growing disconnect between urban human populations and food production, I believe that unique and beautiful plants can play a role in re-engaging people with their food sources. People are often called to beautiful things, as this generates feelings of care in an effort to protect what they deem as “good”. My PhD projects have focused on creating “blueberry-cranberry” hybrid fruit that would improve the sweetness of cranberry and also increase the shelf-stability of blueberry. While selecting “cran-blue” hybrids for fruit production, I have also considered their overall ornamental value as part of the selection process, to entice not only commercial producers but also garden enthusiasts to grow the unique “cran-blue” fruit.
I also came to understand how critical it is to “meet people where they are” and engage people in topics such as fruit production, as I become a professional in the plant sciences. To explain the concept of creating a new type of “cran-blue” fruit, I used a flotation module to demonstrate the difference in fruit density between cranberry and blueberry. At ACG’s Spring Preview, I talked to our visitors about how soluble solids (like sugar, for example) are able to influence the flotation ability of fruit, among many other factors. It was really fun to see our visitors excited about a potential new small berry being available to buy, that lasts longer than a blueberry. To explain the importance of pollinators for fruit production, I extended the module to include samples of male and female bees that were lent to me by fellow entomology grad student Victoria Salerno. I was able to use the fruit and the bee samples to explain to children that all fruits start as flowers, and that those flowers require pollinators to set fruit. For some children, that realization of flowers becoming fruit was impactful. It was a full-circle moment for me to see the children engaged with the flotation module and carefully observing the bees in the petri dishes.
Working at ACG as a horticulture intern this summer 2025 not only expanded my knowledge and experience with the vast collection of annuals and conifers in the garden, but also convinced me of how important ornamental horticulture is for society. I was assigned to the Carson Conifer Garden, the New American Garden, and the Orientation Garden, in addition to building the miniature cranberry bog. The horticulture interns along with Director Reba Luiken and ACG’s new horticulturalist (Jenny Zinniker) planted about 20 new dwarf conifers, all of which were unique selections from Iseli Nursery. In between mulching, planting, and pulling weeds, I experienced many positive interactions with our visitors and was able to see first-hand how much they enjoyed asking the staff questions about the plants we worked on. In a sense, I saw how public botanic gardens in all their glory make people receptive to new ideas and information, which is an opportunity as a plant scientist to talk to people about the importance of landscape stewardship for the benefit of society.
I am very thankful to ACG Director Reba Luiken and the ACG Team for the Horticulture Internship experience I had this summer 2025.