KENNETT SQUARE, Pa. (AP) — Growing the so-called "thousand bloom mum" — a show-stopper at Longwood Gardens' fall Chrysanthemum Festival — takes 18 months and thousands of worker hours. In the week before the annual event, at least six people work full-time prep the plant.

But with fewer young people choosing careers in horticulture, Longwood is working to ensure that the effort and expertise that goes into growing this Japanese specialty plant is preserved for future generations. Three college students are documenting how to successfully raise a thousand bloom mum by creating a video archive that can be used to teach future generations of horticulturists and also spark interest in the field.

"The younger generation can't see the reward of doing this," said Jim Harbage, floriculture Leader at the 1,000-acre (405-hectare) garden and education center in Kennett Square, about 35 miles west of Philadelphia. "It's not enough to have a sense of pride. It's not something that pays a lot of money."

The fear of losing the tricks of the horticulture trade is not limited to growing chrysanthemums. Patricia Binder, spokeswoman for National Garden Clubs Inc., said there is a concern "about the potential loss of institutional knowledge and the loss of gardening knowledge in general."

In an effort to spark interest in the trade, the nonprofit organization annually awards scholarships to students studying horticulture and related fields. Similarly, the American Public Gardens Association has partnered with public gardens nationwide, including Longwood, on the Seed Your Future initiative, which promotes horticulture as a career for young people.

Longwood Gardens decided to partner with the University of Delaware as part of its "succession planning," said gardener Tim Jennings, who specializes in water lilies.

In days past, a young gardener would learn trade secrets from a master gardener. Current Longwood mum master, Amanda Galano, worked in the shadow of now-retired Yoko Arakawa, who brought the thousand bloom mum to the public garden.

Arakawa learned the intricacies of growing the complex plant through multiple trips to her native Japan, where successfully growing a thousand bloom is considered an art some call "high-wire horticulture."

By the end of this summer, the students will have produced nine videos that document part of the mum growing process.

Each student has a different role in documenting the processes. Sophomore Rebecca Ralston, who is studying wildlife and the environment, writes the script for the video. Junior Joy McCusker, who is studying landscape architecture and landscape horticulture design, is "the lens," following the master gardeners around as they work and taking precise notes. Senior Max Gold handles visuals and has used drones, a GoPro and a gimbal camera to get his shots.

"We have to find new methods to add to the toolbox to teach new horticulturists what's important," said Ralston, who admitted she wasn't aware chrysanthemums and mums were the same thing until her first day on the job.

This year, Longwood would like to see its thousand bloom top 1,500 blooms in time for the Chrysanthemum Festival in October. It can't get much bigger, Galano said, because it wouldn't fit through the greenhouse door.

Attention to detail is critical. Some practices are simply hard to explain, Galano said, and a carefully narrated how-to video makes a big difference.

That said, best gardening practices are always evolving, Jennings said. He's confident that while the videos will serve as starting points for newcomers, they'll need to be updated as years pass.

"Gardening is not a stagnant field. The nature of being a gardener is wanting to try something new," he said. "Every year it's, 'What if we did this? What if we changed that?' We're always trying to make things easier and less labor-intensive while balancing that with tradition and not straying too far afield."