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The magic of McAlpin Farm

By Clarisa Diaz, Seasonal Gardener – McAlpin Farm 

Every summer, thousands of visitors admire the beautifully kept gardens of the Preserve. The Azalea Asticou Garden offers a Japanese-inspired meditative and meticulously manicured landscape, while the Thuya Garden offers an array of native and ornamental pollinator-attracting flowers and plants in an intimate space behind a rustic lodge. The Abby Aldrich Rockefeller Garden is the largest of the Preserve’s gardens, with winding paths through various breathtaking garden designs. 


But few visitors know that many of the plants they immerse themselves in are grown at the Preserve’s McAlpin Farm in Seal Harbor, a series of connected temperature-controlled greenhouses with a cut flower farm and holding spaces for hardy plants during the off-season. The farm, not open to the public, has a small staff that works tirelessly to raise thousands of flowers, shrubs, and grasses, many from seed and cuttings through the winter and spring months. The planning and production of plants for distribution across the Preserve is impressive and it is all done using sustainable practices. The gardeners of the McAlpin wash and reuse pots and trays to reduce plastic waste, compost stock plants and other green waste. They use beneficial insects for pest control instead of relying on pesticides.  


Here is a behind the scenes look at some of these practices and how McAlpin Farm makes plant magic happen year after year. 

Starting the day at McAlpin Farm

Germination, propagation, and lots of potting 


McAlpin’s full-time staff include Brenna Sellars who focuses on spring seed germination and Megan Stillman who propagates plants from cuttings. Cassie Banning, the Director of Farm and Gardens, oversees this work, and manages the ebbs and flows of McAlpin – coordinating with all the garden managers on which plants to grow for the next season’s garden designs.  


McAlpin staff is supported by help from all Preserve gardens staff, seasonal gardeners, and volunteers, making up a team that transplants and pots thousands of seedlings, over 13,000 of which are annuals. Native and perennial plants are grown from seed, taking years before they can go out to the gardens or lands. “Plants are being grown or stored all year long. This week I started 50 trays of annual seeds and next week I’ll start another 30. It’s hard to fathom how many plants we grow and how many are in the gardens,” said Brenna. In addition to the gardens, McAlpin is growing over 2,000 native plants for Thuya’s woodlands and 700 plants for the Preserve’s natural lands this season. 


“One of the things I love is that even though you’re doing similar things each season, it’s always going to change a little bit because of the weather and which plants we’re growing,” said Brenna. “There’s always a shift and change. You always have to wrap your head around the new thing. This job allows for so much experimentation.”  


While Brenna seeds, Megan cuts. McAlpin maintains stock annual plants that are grown specifically to take cuts from, the cuttings becoming the next generation of plants. Certain types of heliotropes, like Royal Fragrance Heliotrope and Old Fashioned, as well as Double Azalea Apricot Snapdragons are no longer found on the market and must be maintained each year from cuttings. “This is the last batch of cuttings. It’s very exciting,” said Megan, working on a Mulberry Jam Salvia. “It has beautiful magenta flowers.” In the winter, the staff keeps a succession of stock plants going and times them to be ready for the next season. 

Brenna Sellars (L) and Megan Stillman (R) transplant and propagate plants

Potting happens nonstop at McAlpin. Transplanted seedlings and plugs are placed into bigger and bigger pots, eventually filling all the greenhouses by late spring. Soil depth, moisture, and compaction are all key in getting a plant rooted properly. Repetition builds consistency leading to similar growth across plants. Every plant is labeled as they move positions and get reorganized to make space as the summer approaches. 


A clean greenhouse makes healthy plants 

A very small sample of plants potted by the author

The greenhouse is a beautiful and peaceful place, filled with seedlings and hardy green plants. This healthy environment is made so because of attention to cleaning the greenhouse on a weekly basis. Well swept floors and potting benches keep pests and diseases at bay. Used pots are washed to be sanitized and reused, a huge undertaking. “We’ve switched over to using a lot of fiber pots which can be composted, but certain plants don’t do well in fiber pots because they tend to dry out faster. So, we wash and sanitize all our plastic pots rather than throw them away,” explained Brenna. This amounts to thousands of pots and trays that are deep-clean sanitized at least once per year and reused every season. The inside of the greenhouse is thoroughly sanitized after all plants are distributed to the gardens in the early summer. 

A predatory wasp used to combat whitefly in the greenhouse

Integrated pest management is also practiced at McAlpin. Pest insects in the greenhouse can be controlled with predatory insects, a more natural method than using pesticides. Very small mites and wasps for example can prevent thrip and whitefly populations from spreading. “Once you get whiteflies, they’re hard to get rid of. We have a constant, every other week, input of predator wasps as a preventative,” said Brenna. The beneficial bugs can be found in products such as Thripex, Spidex, and Enermix. 

Royal Fragrance Heliotrope grown at McAlpin

Brenna and Megan think of McAlpin as a unique place to experiment and thrive. “We get to experiment with all kinds of different plants. We grow annuals, perennials, and natives. It’s the best of all gardening,” said Megan. “We’re not just trying to fill the greenhouse with crazy amounts of one type of plant. We get to know these plants and take care of them. It’s wild to see these plants when they’re little and what they become in the gardens.” Because McAlpin is a greenhouse used solely by the Preserve, the goal is to grow a variety of plants that fulfill the garden designs and land management practices. 


From my perspective as a new seasonal gardener, it is certainly an eye-opening experience to see the level of detail and consideration that goes into nurturing each plant from infancy to being planted in the lands and gardens. This is something most people never think about when looking at blossoms in a landscape. I have a newfound admiration for the care that goes into the growing process, and so much more to learn. 


All photographs by Clarisa Diaz. 


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