An old greenhouse, which has not been used to grow plants in several years, occupies the south-facing section of the Arboretum’s lab building, east of the Visitor Center. It had become a random storage space and was falling into disrepair.

During 2023, the land care crew envisioned bringing it back to life and growing native plant plugs for restoration projects. Planting healthy native plugs grown in a controlled greenhouse environment is sometimes favored over spreading seed because plugs can establish in a restoration site significantly faster. Growing plugs is also especially desirable for species that are hard to establish by seed.

For the crew’s vision to become a reality, a lot of work was needed. We cleaned out the various items that had accumulated on the shelves, then assessed the condition of the electronics and mechanicals. The greenhouse’s small furnace did not work, was covered in dust and cobwebs, and had hornet and mouse nests clogging the flue. There were even vines growing up into it from the ground underneath! After thoroughly cleaning the space, turning on the gas, and referring to the operating manual, we got the furnace working again.

The greenhouse has an adjustable window ceiling vent that helps maintain a set temperature, and it had also stopped working. We determined the old coiled thermostat was broken and replaced it. The cooling fan that pulls in outside air to help prevent the greenhouse from overheating on warm, sunny days was, fortunately, in working order. After making these repairs, we hung new grow lights, hooked up timers, and set up tables to hold our trays of plants.

We have ramped up native seed-collecting operations over the last few years, gathering a record 575 pounds in 2023. Typically, land care staff spread all the collected seed at the end of the year. But in 2023 we set aside a small portion of seeds from twelve species to grow in the rehabilitated greenhouse. We selected some uncommon species, such as wood lily, wild hyacinth, and New Jersey tea, to help increase their chances to establish. We chose others, such as lead-plant and compass plant, because they haven’t grown well from seeds spread in our restoration sites.

A few months before putting seeds in starter cell trays, we prepared them for cold stratification. This is an essential step for germinating prairie seeds. They are placed in plastic bags filled with moist sand and then refrigerated at a temperature between 32 and 38 degrees for a few days to four months, depending on the species. Once stratified, the seeds are ready to plant in starter trays.

Each species requires different soil moisture and structure, so we individually mixed soil for specific trays and species, placed three to four seeds in each starter cell, and carefully watered the trays. We check the plants daily to water and care for them as they grow.

So far all the species have germinated well and we are happy to see plants coming up. As of late February, the plants are about one month old – and some species have roots poking through the cells. Eventually, these plants will grow roots that reach anywhere from 5 to 15 feet long at maturity – they still have a long way to go! But we are confident that once planted, they will have a good chance at reaching their potential.

Once the threat of frost has passed, we will carefully choose areas to plant the plugs. In particular, we have our eyes set on some areas at Southwest Grady Savanna, Lost City Forest, and Teal Pond Wetlands. This has been a valuable learning experience and we will use this knowledge in the future to assist our ongoing restoration projects at the Arboretum.

—Arboretum land care crew