Inside the towering high tunnels’ at O’Brien Garden and Trees, are rows of meticulously sown trees, erupting with vibrant green leaves; the branches laden with the beginnings of this year’s fruit crop.

The expansive green space is the result of four-decades of experimentation and the recent move to indoor growing for the agricultural operation.

Inside his two 24-by-48 foot high tunnels, Mike O’Brien grows hundreds of flavors of produce, from Honeycrisp apples to pears to plum trees with apricot branches —though the latter is an experiment that may not prove productive.

O’Brien has been experimenting with fruit for so long that when he talks about his process — things can get complex fast.

“Apricots can be grafted onto plum trees because they’re off the same family,” he said during a interview. “We have grafted some on there, that was just something that was done this spring when they were dormant. We don’t know what the results are going to be. If they go through a winter, if they’re hearty enough to live. But, it’s possible to do that because anything in the same family can be put in the same tree.”

The idea, he said, came from a drive to keep expanding and get the most out of each tree.

“With high tunnel trees we just have so much room to put in there and we wanted another variety and to try the best fruit we can in that limited space,” he said. After decades of outdoor cultivation, four years ago O’Brien moved his apple trees indoors, treating them to a warmer, prolonged season. The move brought his family’s agricultural operation, at 9152 Orchard Circle in Kenai, to another level.

For O’Brien, the choice to move his tree inside and double the growing season was easy.

“There is just no comparison to a high tunnel,” he said, during a recent tour of his orchard.

The plastic wrapped metal skeletons of high tunnels are similar to a green house, except plants are seeded directly into the ground, and no outside heat sources are applied, O’Brien said. But they aren’t necessary, he said.

On warmer days during the winter, temperatures in the high tunnels climb high enough to cause the snow to slough off of the slick, plastic walls of the structure.

O’Brien said he bought his high tunnels through a U.S. Department of Agriculture program administered by the Natural Resources Conservation Service, or NRCS. He is one of more than 70 other growers on the central Kenai Peninsula who use high-tunnels that were, at least in part, paid for through the seasonal high-tunnel program. It allows growers to start planting earlier, elongating the potential growing season — a boon to local commercial producers.

O’Brien said he plans to add another high tunnel to his property next season.

“The key is that you could never grow the fruit outside that is in the high tunnels,” he said. “The season just isn’t long enough for it to mature and the heat just isn’t there. You could never grow plums or pears … the larger the seed the more heat it takes.”

With the addition of the high tunnels, O’Brien said Kenai Peninsula apple growers had comparable growing seasons to those on the west coast of the Lower 48.

The structures also make it easier to monitor the crop environment and immediately address infestations, O’Brien said as he pointed at a thick leaf marred by jagged bug bites.

O’Brien has espaliers, or trellis-like structures designed to control the growth of wood plants by pruning and then tying branches to a frame. His trees are four feet apart, half the normal spacing. This set up is designed to allow the use every inch of space possible, he said.

Tied to the trellises, are yellow sticky pads, called sticky traps, that are used for pest monitoring. The surface of the pads show a record of what insects have been traveling through the environment, O’Brien said.

Also interspersed within the trees are long, thick-bristled paintbrushes. Orchard manager Michelle LaVigueur explains that they use artist’s tools for cross-pollinating blossoms by hand.

“We only use the paint brushes to pollinate blossoms we have isolated for breeding,” LaVigueur wrote in an email.

Apple trees cross-pollinate, thought it takes two varieties, as do sweet cherries. The sour cherries at the orchard are self-pollinating, meaning a gardener can grow one variety and still get the fruit, bees and insects do all of the pollinating.

While O’Brien and LaVigueur rely on Alaska’s native bumblebees to find the high tunnels and pollinate their apple trees — the two also ship honeybees in to pollinate some of their outdoor plants — and for the family’s honey supply.

Just outside of one of O’Brien’s high tunnels, an assortment of rainbow painted boxes brim with distracted bees.

Walking inside of the buzzing sphere wouldn’t upset the hives as the bees are busy working to gather pollen and make honey, O’Brien said.

While the honeybees are good at some types of pollinating, they are not good at pollinating apple trees in the high tunnels.

“They tend to become disoriented and end up in the top of the high tunnel where they can’t escape,” Lavigueur said.

Both O’Brien and LaVigueur spoke highly of the NRCS high tunnel program — each said they would encourage area growers to consider investing in one.

While growers with smaller high tunnels might shy away from growing large trees that could take up a lot of space, LaVigueur said she easily grows an apple tree in her personal high-tunnel.

“I have saved a 10-foot space for one apple tree,” she wrote in an email. “The tree is grafted multiple times, one variety on each branch. As it grows new branches, I will keep adding more variety (at least one more that it can pollinate and produce fruit).”

LaVigueur, who used the NRCS high tunnel program to put her personal structure up as well, said it can be intimidating to visit O’Brien’s orchard and see wall-to-wall apple trees.

“I know a lot of people think they don’t have room for that, but when I say 10-feet, well that’s not really a lot of space,” she said.

LaVigueur’s personal apple tree started with her favorite variety, Silken.

“Its flavor is bright, sweet, juicy with pineapple undertones,” she wrote. “(It) always produces a heavy crop.”

Next, she plans to add Zestar, as it is a variety of apple with a good flavor and it keeps well and William’s Pride which is both tasty and known for its fragrance, she wrote.

“This way I can have apples for sauce, pies, fresh eating, an juice and save valuable growing space for other crops,” LaVigueur wrote.

While O’Brien’s products are sold at farmers markets around the central Kenai Peninsula, LaVigueur said more people seemed interested in visiting the orchard, buying a tree and seeing full grown trees.

The orchard will be open every Monday from 10 a.m. to 4 p.m. for community members interested in learning set-up, tree maintenance and high tunnel usage.

On September 14 from 2-4 p.m. O’Brien will host a public apple tasting, the orchard’s first since moving the crop indoors, LaVigueur said.

At that time, O’Brien said, people interested in growing their own apple trees will be able to try the some of the orchard’s varieties — with the option of selecting one to have O’Brien graft and have ready for the spring of 2015. There is a measurable amount of pride in his voice as O’Brien talked about growing and grafting apple trees for the past 40 years.

“These apples that we have are from all over the world,” he said. “High tunnel space is so valuable. There’s no sense in growing anything but the best.”

Kelly Sullivan can be reached at kelly.sullivan@peninsulaclarion.com and Rashah McChesney at rashah.mcchesney@peninsulaclarion.com

Photo by Kelly Sullivan/Peninsula Clarion Honey bees are unleashed every spring outside the high tunnels at O’Brien Orchards for pollinating the various plant species staying warm inside the towering plastic containers, Friday, May 20.

Photo by Kelly Sullivan/Peninsula Clarion Mike O’Brien’s stands between rows of the grafted apple trees packed inside the O’Brien Orchard high tunnels, Friday, May 20.