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How One Man Is Managing to Grow Tropical Fruit in the Rocky Mountains

In addition to bananas and figs, he also has a one-acre outdoor food forest brimming with berries, olives, stone fruit, and more.
All photos by the author.

Jerome Osentowski grows tropical bananas in the Rocky Mountains. Not in a particularly fertile or comfortable part of the Rockies, either: He resides in Basalt, Colorado at 7200 feet above sea level, where the soil is mostly red clay. Not much grows naturally besides resilient trees of piñon and juniper.

"We had very little soil to start with," Osentowski, founder of the Central Rocky Mountain Permaculture Institute, says. It's an arid and harsh climate, where the weather easily drops to below-freezing during the winters.


Yet in a series of greenhouses on his property, he is growing five different types of bananas, giant towering trees ripe with Mediterranean figs, and a cornucopia of tropical goods, like taro, cherimoyas, mangoes, sweet potatoes, and papayas.

He also has a one-acre outdoor food forest—20 years of age—brimming with over 200 varieties of edibles, including mulberries, hazelnuts, lamb's quarter, cherries, gooseberries, garlic, apricots, perennial broccoli, apples, currants, olives, and pears.

Using Greenhouses To Extend The Growing Season

His property is located in zone 6, a category on the USDA hardiness zone map that helps growers determine which plants are most likely to thrive at a location. His ingenious use of greenhouses gives him a range of up to zone 11, meaning his minimum average temperature doesn't drop below 40 to 50°F.

While the use of greenhouses to elongate the growing season isn't anything new (humans have been using this technology since the Roman times), what sets Osentowski's system apart from conventional models is its energy efficiency. The heating and cooling system in his tropical greenhouse is powered with just three 90-watt fans—the equivalent of a couple of old light bulbs.

Osentowski in one of his greenhouses.

Unlike conventional greenhouses, which are energy-intensive, Osentowski's system uses fans to drive warm air into the soil. Certain design elements, like a sauna, water tanks, insulation walls, a hot tub, and rock beds, are passive heating and cooling features that trap heat. He also has a bed of pollinator plants he grows outside of the greenhouse to draw bees and butterflies. "With climate change we're getting a lot of extreme weather conditions and with the greenhouses, you can pretty much alleviate those external conditions," he says.


But while a greenhouse can stabilize temperatures, Osentowski believes the future of climate resiliency in fact lies in establishing a multi-layered forest system, with trees as a foundation.

Ostenkowski's outdoor food forest.

Using Agroforestry To Create An Regenerative Ecosystem

Each of Osentowski's greenhouses has all the layers of a forest, from canopy to ground cover. Nothing is grown on sterile trays and there are no grow lights. It's a multi-layered food forest, prioritizing perennials. Unlike annuals, perennial crops don't require tilling. This keeps the carbon stored in the soil as opposed to the air.

It's a big contrast to the monoculture growing operations of modern-day greenhouse systems. While organic growing methods are employed in these high-tech greenhouses, the necessary inputs for fertilizer, weed suppression, and pest control are still produced off site. These commercial greenhouses are still dependent, he stresses, on fossil fuels.

While those greenhouses are efficient at producing food, Osentowski says that's a model that isn't long-term or ideal for impoverished communities who don't have access to external inputs.

His biggest tip? Build soil from within the system.

"All of the soil that we're building here is from sheet mulching and hugelkultur and using animal integration," he says. "It's one of many agroforestry models that keeps all the soil covered." Mulch also helps with water retention.

The Central Rocky Mountain Permaculture Institute is essentially a giant worm factory. Reach your hand into the soil at any part of his farm and you'll be greeted by a plethora of red wrigglers, who are digesting organic matter and turning it into compost.


Osentowski's operation essentially feeds itself. Because the plants are grown in a multi-layered system, it self-mulches. Like in a forest, fallen leaves and decaying plant matter add nutrients into the soil. Herbaceous plants like comfrey and ground crawler vegetables like strawberries benefits from this forest system; the trees provide them with shade. The system mimics that of a forest. The main difference is that each species has been carefully curated and most of them are edible. He intersperses nitrogen-fixing trees like black locust throughout his operation—trees that take nitrogen from the air and put it into the soil.

The outdoor food forest.

It's not just about growing food, it's about growing an ecosystem, using trees as an anchor to regulate temperatures and draw up water levels.

This is a philosophy that is common with agroforesters around the world, who are set on building systems resilient enough to deal with the inevitable fluctuations of climate change.

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"The regions that are tested by incredibly hot temperatures get really degraded soil and are extremely remote with limited water sources," says Charlotte Jongejan, head of marketing and communications for Land Life Company. "Trees there have low survival rates, anywhere from 5 to 15 percent. But those are the regions we specifically aim for."

Land Life is an Amsterdam-based company that restores ecosystems in extreme climates around the world. In the past, they have planted mango and avocado trees in extreme parts of Kenya and have established productive crops in degraded soils along the Mediterranean coast.


"By having a tree in the ground, you are creating a way for the ground water levels to rise. Instead of pumping water into the ground, you're stabilizing and bringing that water up again," she says.

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Their latest project is working with the Minawao refugee camp on the north side of Cameroon, where they will be planting 40,000 trees in conjunction with the UN Refugee Agency.

"We are building the world's first green refugee camp," Jongejan says. "Deforestation is leading to a huge migrant crisis all over the world. We're tackling this problem in the far north of Cameroon where it's extremely dry."

The company will be planting fruit and nut trees around the perimeter of the camp and outside of it, a forest of fast-growing shade trees like neem and acacia that will act as a forest and a buffer zone. They will also be establishing a plant nursery in the camp and teaching the community how to propagate seedlings.

"There will be no irrigation needed after planting," Jongejan says.

To increase the survival rate of the trees, Land Life uses what they call a Cocoon, a biodegradable container fashioned out of paper pulp and sealed with a wax coating to ensure water tightness during the first year.

Using Fungi To Aid Water Retention Rate Of Trees

The surrounding soil of each tree that Land Life plants is inoculated with mycorrhizal fungi, which increases the absorbent surface area of roots by a factor of 100 to 1,000.


"Mycelium increases the uptake and retention of water and nutrients, which is a major benefit in desert conditions," Peter McCoy, founder of Radical Mycology, an organization dedicated to educating people about fungi, says.

Fungi provide multiple benefits to plants: they can adjust pH levels of the soil, release antibiotics, and scavenge for fertilizers.

"They make nutrients accessible that might otherwise be bound up in the soil," he says.

Banana trees.

Garden of Eden

Indeed, it is this holistic approach to growing food, from trees to fungi root systems, that creates a system that stands the test of time.

Osentowski notes that his own property was at a USDA hardiness zone 3 when he first started farming and has since shifted over three climate zones to zone 6. In short, it's been getting hotter.

In his forty years of working with the land, he has personally seen the effects of climate change.

"We used to get four feet of snow. Now we only get about one foot that stays," he says.

Grapes from the greenhouse.

Yet there is not a shortage of food on site. Polyculture perennial tree systems, which make up the core of Osentowski's farm, are much more adapted to weather fluctuations than annuals are. "In the places where people are going to be most affected by climate change, they need to convert monocultures to perennial polycultures. We need to use the animals, grasses, and trees together," he says. "Agroforestry is the way,"

At 20 years old, Osentowski's food forest is the oldest, most established permaculture food forest in the United States. As I follow him through the dense understory of his outdoor forest, I am overwhelmed by the amount of food on just one acre. He's an especial fan of the Pakistani mulberries, and climbs into the tree to fetch a handful for me and my friends His farm is a land of plenty in an area where not much else can thrive. The Nanking cherries—bright red and sweet—have also just come into fruit. Among the 200 varieties of edibles in his outdoor food forest are 15 plum trees, 20 apple trees, 25 grape trees, oats, barley, sunflower, 15 pear trees, five different types of nut trees including hazelnuts and pecans, and seven types of mulberries.

Within a couple of minutes, I am already full from the woodland stroll. Even during the winter, when the outdoor section is covered with snow, there's still plenty of food available in his greenhouses, which are currently teeming with squashes, beans, and tomatoes. The fig and banana trees act as a canopy layer, absorbing excess heat.

"I call this stream of consciousness gardening," he says. "There is no end or beginning. Things die and simply grow back again."