JEFFERSON COUNTY — The kidnap victim was a rat-tail cactus.

A door at Timberline Gardens, the west metro nursery that’s been an institution for nearly two decades, had been left unlocked last fall, and someone had snuck in and nicked the hanging plant with the trailing, six-foot-long arms.

Timberline horticulture director Kelly Grummons tracked the cactus by the tendrils it shed all the way to the nearby porch of the alleged thief. Then he reclaimed the houseplant that he’d owned since his childhood in South Dakota.

But unlike the venerable specimen of Aporocactus flagelliformis that returned to hang in one of Timberline’s greenhouses, Timberline itself will make a permanent exit at the end of September, to be eventually replaced by a medium-density residential development.

“It’s always a bit sad when something like that makes way for residential,” said Panayoti Kelaidis, senior curator at the Denver Botanic Gardens. But “you need a lot of space for a garden center, especially a nursery garden center,” and often, the only retirement plan for those who own such establishments is selling the land.

In the case of Timberline, that land is 10 acres near the corner of West 58th Avenue and Ward Road. It will be combined with two other parcels into the 26-acre, 322-unit The Farm at Timberline. Confluence Companies’ plan has been submitted to the city of Arvada for approval; if it’s OK’d, groundbreaking will occur in about a year.

Timberline’s Jill and Charles Richardson, partners with Grummons in the business, knew that closing out this chapter in their lives would be an emotional rollercoaster.

“We’ve had so many people come in literally sobbing. And of course when they start, I start,” Jill Richardson said.

But running an establishment that grows many of the plants it sells — as opposed to ordering them from wholesalers — and deals as well in soil, compost, rock, fertilizer, tools and classes, is often grueling.

And then there are the winter months with fewer customers, but no cessation in expenses.

“I’m not up for signing on for another 15 to 18 years at this age,” said Charles Richardson, who’s 67; Jill is 59.

Both of them help Timberline’s employees handle the phones, work the cash registers and move the plants during the 12- to 14-hour days and seven-day weeks of the gardening season.

Grummons is the plantsman of the trio, with many Plant Select introductions and a new high-traffic warm-season turfgrass to his credit. He also develops and grows cold-hardy cacti and is one of the state’s most sought-after horticulture experts. He grows prickly pear cactuses for their fruits and harvests them for local chefs who turn them into barbecue sauce or sorbet.

On a recent spring afternoon, Grummons walked through the greenhouses, the almost imperceivable scent of damp soil in the air. It was faint because so many of the plants are xeric or low-water varieties; signs advised staffers “Do not water” or “do not water this weekend.”

There was a bright pink coleus called “Mars Landing” on which Grummons holds the patent, but which he said “hasn’t had its dance yet.” A beaked tree yucca whose seeds he collected in the Chisos Mountains of west Texas. A hardy agave he found in the Guadalupe Mountains of New Mexico. And on and on.

“I’m really interested in desert evergreens. Our landscapes here in the future will be dominated by low-water plants, so the native manzanitas, junipers, hollies will be very important,” he said.

“This is a native kinnikinnick” — a low, shrubby groundcover also known as bearberry. “Almost all the kinnikinnicks being sold now are from Canadian sources, Eastern sources, places where it’s gray and wet. But this strain is from Boulder County, and no one else is growing it.”

At the back of one greenhouse stands a row of tall, ferny, blue-tinged evergreens in pots. They’re a variety of Arizona cypress that renowned plant hobbyist Allan Taylor is developing with Grummons. Taylor found the seed on Cooke’s Peak in New Mexico, and Grummons is growing the trees.

“Every one of these plants I look at, I know where they came from,” Grummons said. And then he heaved a sigh.

Is it one of relief?

“No, not relief … the sound would be, my head’s in the sand. … Denial,” he said. Grummons, at 52, doesn’t know what he’ll do next.

“He’s an incredible asset in and of himself,” Kelaidis said of Grummons. “There’s nobody who comes close to him when it comes to knowledge about natives and Xeriscape. He’s a plant nerd and also the world’s nicest person. He’s also a phenomenal designer.”

The Richardsons are retiring to their home near the garden center where they’ve lived since 1985; it’ll be one of six single-family homes that the plan for The Farm at Timberline includes, along with a clubhouse and vegetablegarden. Grummons, though, has what could be the most important decades of his career ahead of him.

“It’s very scary to most of us” in the horticulture world, Kelaidis said. “He could be stolen by California or Utah, someplace where land is cheaper.” Kelaidis admitted that’s a selfish worry, and not one suited to the sunshine of a spring afternoon. “I have no doubt that he’ll land on his feet and do tremendous.”

Together with their staff, the trio can legitimately be said to have helped educate gardeners, not just in Jeffco but state and region-wide.

So it’s not surprising that the question on most Timberline customers’ lips is this: Where will they get their stuff?

“We answer that question easily 50 to 100 times a day,” Jill Richardson said. “We have such a specific niche with native and xeric and oddball stuff that’s hard to find.”

Charles Richardson said he hopes to keep the store’s phone line on for as long as a year after the shutdown. He said he’ll be answering it to help customers find sources for plants and products such as soil and compost.

Customers also ask where the mini horses, Lucky and Snippet, who spend weekends at Timberline, will go. Jill Richardson has that answer ready to hand: They’ll go home with the couple to the same place they now spend weekdays.

But as for how you gear down a business of 18 years?

“We’re about to find out,” Charles Richardson said.

Susan Clotfelter: sclotfelter@denverpost.com; 303-954-1078 or twitter.com/@sclotfelter