OSU horticulturist helps Oregon residents fortify lawns and landscapes in the face of climate change

Weston Miller teaches people how to turn their lawns into carbon sinks and how to use plants to protect buildings from fire and wind.

Oregon State University horticulturist Weston Miller in his Portland garden. Miller stands next to a pineapple guava, a South American fruit shrub that can survive Oregon’s longer, warmer months. (Alex Baumhardt / Chronicle of the Capital of Oregon)

Weston Miller is helping the people of Oregon prepare for a future of more intense rains, winds, droughts, fires and insects.

Miller has headed the West Multnomah Soil and Water Conservation District, has been a master gardener and community and urban horticulturist with the extension service at Oregon State University for 14 years.

He teaches people to arrange their properties with plants that can hold more water, stay intact in wind and rain storms, and those that can even protect buildings from fire.

He said more people in Oregon should start thinking about climate change when it comes to the landscaping they undertake.

“From drought to algal blooms in freshwater lakes, freezing rain, windstorms, hot and scorching winds, we’re going to expect an increase in frequency and magnitude of such events. So all of that definitely has an impact on people’s properties, ”Miller said.

OSU’s Master Gardener program volunteers answered more than 2,500 questions in the Portland area alone last year, Miller said, including many about planting drought-tolerant plants that didn’t. not need a lot of water.

This summer, the entire state experienced moderate to exceptional drought, according to the US Drought Monitor.

Native Oregon plants like rhododendrons and azaleas that are well equipped to survive the region’s Mediterranean climate were scorched and stressed by the heat dome in June when temperatures in parts of the state hit 118 .

“The evidence that climate change is impacting local conditions is pretty clear,” Miller said.

Stressed Oregon’s Iconic Plants and Trees

Native Oregon shrubs and trees like Douglas firs and red cedars are stressed by hotter, drier summers and become more susceptible to invasive insects, fungi and disease, Miller said. This happens in urban and forest areas.

Insects capable of detecting stress in certain plants and trees have proliferated in large numbers, such as the lace bug. It detects a specific compound that azaleas and rhododendrons release when stressed and weak. Bedbugs attach themselves to these plants and feed on the undersides of their leaves.

Because insect metabolism is based on outdoor temperatures, “if things get a little warmer then we’re going to see insect life cycles with an extra generation per year,” Miller said. “So it’s kind of like a double punch for these plants that were once the mainstays of Pacific Northwest landscaping.”

Elizabeth Hodgson is a landscape designer in Oregon and CEO of the Oregon Landscape Contractors Association. She answered calls this summer from people trying to save their rhododendrons.

“They don’t need a lot of water, but the heat has been very damaging to them,” she said. “There was really nothing we could do. “

Miller said fruit trees have become particularly susceptible to fungi, as well as some varieties of roses. Overall, he doesn’t recommend home gardeners to plant fruit trees.

“I would say that people’s time and energy would be better spent just buying delicious apples at the farmers market, from people who are equipped to take care of trees properly,” he said.

Landscapes fortified by the ground

To start fortifying properties against the impacts of climate change, Miller tells people to start with their soil.

“This is one of the very first things you can do to help protect your property or plants from drought is to prepare the soil well,” he said.

This involves adding organic matter like compost to the soil and adding woody mulch to the surface to help the soil maintain moisture and stay cool. He said that a healthy layer of soil called humus, where the soil is dark and filled with organic matter, can stay in place for 1,000 years or more.

“This is the best step people can take to protect their landscape from drought and get plants off to a good start,” he said. “And one of the biggest mistakes I see people make is that they just don’t take the time and effort to properly prepare their soil for new plants to settle.”

Focus on drought resistance

Despite the stress many native plants endure as extreme weather events occur more frequently, Miller suggests planting first native species of flowers and trees accustomed to the region’s Mediterranean climate. Much of Oregon is considered such a climate because of its latitude, proximity to the ocean, and hotter, drier summers and wet winters, he said.

As the state experiences longer hot spells, plants that survive in California now have an even better chance of surviving in Oregon. Subtropical plants like pineapple guava or feijoa, a fruiting shrub native to parts of South America, could one day grow in Oregon, according to MiIller.

“I would just like to warn against plants with high water requirements,” he said. “Because we know we’re going to keep dealing with drought, and it’s going to get more and more expensive to keep watering things. ”

Hodgson said more of his customers are interested in creating Xeriscapes. Such landscapes which require minimal water and use efficient irrigation systems like drip lines which slowly apply water at low pressure.

She said that most customers, however, are not motivated by environmental concerns.

“Lately, due to the warmer and warmer weather, there is concern about water use mainly due to the high cost of water,” Hodgson said. “Especially for customers with larger properties, the incentive is to reduce the cost of water. “

Fire resistance planning

Miller said reducing the risk of forest fires to a home or building begins with creating a buffer zone.

“Having an irrigated landscape, making sure the trees are shaken and there is not a lot of brush is the first thing people can do,” he said.

Tree delimbing involves removing the lowest branches. Dead and dying trees should also be removed, as in addition to burning quickly, they can crash into homes and other structures, he said. They are also dangerous in extreme wind and rain.

According to the National Fire Protection Association, the goal of landscaping around a building in a forest fire risk area is to keep a potential fire on the ground and out of the canopy. To do this, the association recommends getting rid of small conifers that grow between more mature trees and, when planting trees, keep them at least 30 feet away from dwellings and space them so that each crown or 6 to 12 feet from each other.

Recommendations from the US Department of Agriculture include planting shrubs and flowers with soft, green leaves near buildings, avoiding anything that contains twigs, needles, waxes, and oils.

Harnessing the power of lawns

Lawns get a bad rap, Miller says.

“They’re actually very good at taking carbon from the air and getting it into their root system.”

Carbon dioxide sequestration and storage are considered essential to slow climate change.

Special techniques, such as mowing mulch, can turn grass into fertilizer. Mulch mowers have special blades that cut grass into tiny shreds that dry out and quickly disintegrate, returning nutrients from the mows to the lawn and soil, reducing the need for synthetic fertilizers.

“If one practices specific mowing practices, such as using a hand mower, electric mower or mulch mower, this is in fact a reasonably land use option. sustainable, ”he said.

Miller said the environmental benefits of a lawn disappear when people use gasoline mowers, leaf blowers, and lots of fertilizer.

Lawns can also become problematic if invasive weeds proliferate.

Due to the rising temperatures, weeds that have typically been dormant over the winter will grow and produce shoots earlier in the year.

“Expect to see a change in weed distribution, both in terms of latitude and elevation,” Miller said.

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