Growing shade: Inside the work of Scissortail Park’s arborist

Sam Grimmett is sitting on one of the trees he couldn’t save. 

The massive piece of trunk now rests in Lower Scissortail Park, where it has found a second life as an unofficial bench. Grimmett remembers working on the tree when crews discovered that, beneath the surface, the inside had rotted. 

For Grimmett, trees coming and going are part of the job. There are, after all, a lot of them to keep track of. 

Grimmett is the only arborist on Scissortail Park’s horticulture team, caring for nearly 2,500 trees across 85 acres. By his calculation, there are about 2,080 working hours in a year. 

That gives him less than an hour per tree. 

Some need considerably more. Others, thankfully, need considerably less. 

“Often what it means is I do the same thing over and over again at a high rate of repetition,” Grimmett said. “I either need to do the same thing 2,500 times or I need to figure out which ones I’m going to do it to and which ones I’m not.” 

Eventually, he hopes to have mature trees on roughly four-year rotations for trimming, soil amendments and other maintenance. 

Seven years into his time at Scissortail, Grimmett has watched thousands of trees establish themselves in the heart of Oklahoma City. He knows which ones took off, which needed a little help and which are content to take their time. 

And he has a pretty good idea of what they’ll eventually become. 

From New Zealand to Oklahoma 

Grimmett’s path to caring for thousands of trees in downtown Oklahoma City began more than 7,000 miles away. 

Originally from New Zealand, he arrived in Stillwater in 2003 after meeting an Oklahoma woman who had traveled to New Zealand for veterinary training. 

“I had nothing better to do with my life than go and see what that Oklahoma girl was doing,” Grimmett said. 

His previous trips to the United States had taken him to places like Los Angeles and Florida. Oklahoma in February was different. 

“I did not bring enough clothes,” he said. 

The couple eventually lived in South Carolina and New Zealand before returning to Oklahoma City in 2009. By then, they had two daughters and were looking for somewhere to settle. 

“It’s hard to keep an Oklahoma girl out of Oklahoma for a long period of time,” Grimmett said. 

Grimmett spent roughly 15 years working for Professional Tree Care, climbing, trimming and removing trees across the metro. His work included caring for the Survivor Tree at the Oklahoma City National Memorial. 

After contracting Rocky Mountain spotted fever, Grimmett began looking for a way to stay in arboriculture without continuing as a production climber. Around the same time, a position opened at Scissortail. 

“Some days I like to think about it as my penance for all of the trees that I cut down over the years,” Grimmett said. “Now I’m having to make them grow in imperfect soil with imperfect water and the occasional hooligan pulling a branch off the tree.” 

Today, his connection to the Survivor Tree continues at Scissortail. 

Among the park’s collection is a clone of the Survivor Tree — one Grimmett said is largely left to grow without intervention. Unlike most of the trees under his care, Grimmett cannot simply decide to prune or treat it without permission. 

The reason carries considerably more weight than the average pruning decision — according to Grimmett, the Scissortail clone is first in line to replace the original Survivor Tree should something happen to it.

Learning how to grow a park 

When Scissortail opened, Grimmett quickly learned that planting thousands of trees was one thing. 

Getting them to grow in the middle of a city was another. 

“Urban soil and urban water cause more trouble than I had expected them to,” Grimmett said. 

The northern portion of the park was built on remediated urban land, followed by construction and imported soil. Add irrigation using water from Scissortail Lake, and Grimmett found himself dealing with soil compaction, high pH and other conditions that made it difficult for the young trees to access the nutrients they needed. 

During the park’s first year, nearly all the trees were yellow. Grimmett said many grew only about a quarter- to half-inch. 

The problem, he determined, was iron. 

When soil pH gets too high, trees can struggle to access iron already present in the soil. Grimmett began injecting a fertilizer containing chelated iron into the ground around the trees. 

The response was dramatic. 

“I could actually watch the color on the trees changing like traffic lights,” Grimmett said. 

The following year, he said growth jumped to about 18 inches. 

“It was an absolute game changer for the park.” 

The troubleshooting hasn’t stopped. 

A golf cart ride through the park with Grimmett comes with frequent stops. 

Along the promenade, one tree catches his attention because of the way its branches are growing. Grimmett explains that it has been getting too much nitrogen, causing excessive growth. He has applied a growth inhibitor and is waiting to see how the tree responds. 

Elsewhere, there have been bagworms to contend with. The 2020 ice storm nearly became a much bigger problem, although the trees’ youth worked in their favor. 

“They got really good at yoga,” Grimmett said. “There was a lot of them doing strange positions and touching their toes.” 

Despite the challenges, Grimmett said losses have remained within expected ranges for a landscape of Scissortail’s size. More importantly, after the difficult first years, the trees became established. 

“The last five years have been extremely successful for tree growth,” he said. 

‘I just want shade’ 

Grimmett has a simple way of describing what he ultimately wants from Scissortail’s trees. 

Shade. 

And after seven years, he’s beginning to see it. 

Unlike when the park first opened, Grimmett now notices visitors deliberately settling beneath trees to escape the Oklahoma sun — sometimes sitting on the lawn with a book beneath a canopy that once barely existed. 

“I get good feelings from that,” Grimmett said. “I grew that tree that that person is sitting under.” 

The need for shade is more than aesthetic. 

Grimmett recalled an Oklahoma City forestry heat-island study that measured the surface of the Children’s Garden at 160 degrees, something he attributed to synthetic surfacing designed with air pockets to soften falls. 

For the future, he wants to strategically add trees, shade structures or other features that can reduce those extreme surface temperatures. 

And as the existing trees continue growing, shade itself will reshape the park. 

“The lawn guys want to have emerald green Bermuda everywhere,” Grimmett said. “I just want shade.” 

A park still growing up 

From the top of Overlook Hill, much of Scissortail stretches out below, with the Oklahoma City skyline rising beyond it. 

It’s also a good place to see just how young much of the park still is. 

Grimmett doesn’t think about its trees on a single timeline. 

An Oklahoma redbud might have a lifespan of around 25 years, he said. Live oaks can potentially live for centuries. American elms grow quickly. Blackjack oaks take another approach entirely. 

“They don’t trust anything,” Grimmett said of the blackjack oaks. “They don’t trust the Oklahoma weather. They’re extremely conservative.” 

Trees also need time simply to recover from being transplanted. Grimmett said newly moved trees initially devote much of their energy to establishing roots before significant growth becomes visible above ground. 

At Scissortail, that establishment period has passed for many of the trees. 

Now they’re growing. 

And that means the landscape around them will eventually have to change, too. 

In roughly another decade, Grimmett expects shade from growing trees to begin changing what can survive beneath them. Bermuda grass will give way in places to shade-tolerant grasses. Sun-loving annuals and perennials will have to be replaced. 

In some areas, he expects an even bigger transformation. 

“This area here behind us, for example, in that 15- to 20-year mark, that will all be deep shade,” Grimmett said. “The trees will have joined and connected with each other and created a full forest canopy.” 

For an arborist, that’s exactly the point. 

Looking beyond the trees 

It doesn’t take long riding around Scissortail with Grimmett for the conversation to wander beyond arboriculture. 

A few butterflies that resemble monarchs prompt a discussion about Scissortail’s role as a Monarch Waystation. Grimmett has helped tag monarchs moving through the park before and remembers periods when they seemed to be everywhere. 

So he takes the golf cart in search of a few. 

It works. 

Among the flowers, a monarch lands with a small tracking sticker already attached to its wing. 

The moment is representative of the larger landscape Grimmett works in. Trees may be his specialty, but they exist alongside grasses, flowers, insects, birds and the work of the rest of Scissortail’s horticulture team. 

During the tour, Grimmett stops at the Children’s Garden, where coworker Deb and other team members are treating weeds. Deb manages the Children’s Garden and vegetable garden and has also worked with Grimmett on another of the park’s unusual landscape features — its floating islands. 

Grimmett said the pair were “integral” in developing the islands, experimenting with several approaches before settling on a combination of coconut husk and compost.

Scissortail’s collection now includes roughly 150 woody species and carries a Level II arboretum accreditation.

For Grimmett, all of it means there is almost always something new to figure out. 

Seven years into the job, he has already seen Scissortail change dramatically. 

His wife, who grew up in western Oklahoma, sometimes recognizes the grasses and wildflowers planted throughout the park as the same ones that grew around her family’s farm. Grimmett jokes they could have taken a lawn mower with a bagger to the fields and used what they collected to plant Scissortail. 

But he also takes satisfaction in seeing those Oklahoma plants succeed in the middle of downtown. 

For all the chemistry, pruning schedules, pests, storms and thousands of individual trees involved, Grimmett’s vision for what he is building is considerably simpler. 

“I do see it as kind of like a giving back to the world and the world of Oklahoma City,” Grimmett said. 

Someday, he hopes, a family will find one of the trees he helped grow. 

“One of these days a family will be able to sit in the shade of one of these trees and drink water on a hot day and entertain themselves with the birds and the lake and the fish that we’ve provided,” Grimmett said.