Experts offer tips on how to care for trees

Gardens are beginning to flourish with brightly colored flowers, honeybees are buzzing, and birds are delighting neighborhoods with their unique tunes.

This time of year, gardening is at the top of the minds of many Oregonians. But for those who have trees on their properties, or are looking to plant trees, it can be intimidating and overwhelming to figure out where to start and how to best care for trees.

Have no fear though — three of Oregon’s experts are here to help you find your confidence when it comes to conifers, spruces and other types of trees.

The basics before you plant

When planting a tree, it’s important to find a good spot. This means making sure the tree will have adequate sunlight, shade, airflow and space to grow.

“A lot of trees, if they’re in the right environment, will grow and thrive,” said Gabe Blustein, yards department manager at Portland Nursery. “Part of selecting the right tree for the right space is making sure it has room to grow. A lot of times, city trees are too close to buildings or powerlines and require emergency pruning.

There are specific requirements that vary from city to city that dictate what homeowners are responsible for when it comes to tree care. In Portland, Portland Urban Forestry specifies requirements for tree care. Often, homeowners must have permits to do any work on trees in the city, including pruning and attaching lights, Blustein said.

“It can seem overwhelming at first for homeowners. I recommend that people reach out to their city and get the information they need and get their proper permits,” Blustein said.

Watering and pruning

Once a tree is planted, it’s important to water and prune it consistently.

Gary English, owner of Landsystems Nursery in Bend, Oregon, suggests watering trees about an inch to an inch-and-a-half of water per week. You can use a rain gauge to measure.

“You should water it well once a week, then leave it alone,” English said.

If you’re unsure of whether you need to water a tree, you can use a soil probe to take a soil sample. Kevin Carr, vice president and division manager of Bartlett Tree Experts in Clackamas, Oregon, suggests using a long screwdriver (about 12 inches) to insert into soil.

“If you meet a lot of resistance while taking a soil sample, that probably means it’s time to water,” Carr said.

Carr, a certified arborist, suggests waiting for trees to become established before pruning them.

“After a tree is planted in the first three to five years, let it grow and watch it grow. After that you should do regular pruning cuts. That will make a large difference for the tree for the next 15 to 25 years,” Carr said.

However, some trees, like fruit trees, may require more frequent pruning, Blustein said. Fruit trees may need to be pruned once a year or every couple of years depending on their size.

Problems to watch for

“There are a lot of little ways that damage reveals itself on trees,” Blustein said. “It’s natural for trees to have some damage but a lot of them are resilient and can survive.”

Signs to watch for include the vibrancy of leaves; whether leaves are dropping during the time of year they should be sprouting; if leaves are curling; and if leaves are black or brown at the edges. Another sign to be wary of is woodpecker activity because that can be a sign of bark beetles, which cause significant damage to trees, Carr said.

To tell whether a tree is thriving, look at how well it is flowering and the size of its leaves, English said.

“If a plant is starving to death, it will have very small, juvenile leaves,” English said. “A stressed plant is more subject to disease or pathogenic activity. You can look at a tree and see that it’s not doing well.”

One way to check for problems is to compare trees to each other.

“If there’s one that looks healthy, you can use that as an index if it’s the same plant,” Carr said. “You’ll be able to tell if the color is not as vibrantly green or if you see leaves dropping during the time of year it should be growing, if leaves are curling, or if they are black or brown.”

The most common error English and his staff see customers struggle with is planting trees too deep.

“The soil gets on the trunk of the tree when it should be at ground level or higher. I recommend they plant it an inch or two high,” English said.

When using bark, English suggests monitoring the moisture around the tree and not placing bark right against the trunk of the tree. He suggests only using a couple of inches of bark.

Inconsistent watering is another common issue.

“You don’t want to overwater, and you don’t want to underwater. I recommend building a tree well, like a moat. Fill it with tree stimulator and water, at least in the first season, and then the moat can go away,” English said.

Young trees can easily be overwatered, while mature trees need their root systems to be moistened, Carr said. He suggests watering just enough to get trees established, then follow up only as needed for a tree’s first three years.

“Most problems stem from inadequate moisture levels,” Carr said. “Every other year, we have a long drought and our plants aren’t adapted to that. We used to have rainfall by Labor Day but now it’s late September or early October.”

Other issues to be wary of include inadequate mulching, fungi, pests and harsh climates.

When to call a professional

Using online resources such as the Pacific Northwest Chapter of the International Society of Arboriculture’s website (pnwisa.org) and working with local garden centers and arborists are ways to get support with tree care.

“Those are the people who are plant experts and understand how plants grow,” English said. “Talk with your local garden centers. If you get into trouble with a tree, then you can call an arborist to have it taken down.”

Most arborists will do a first inspection free of charge, Carr said.

“Don’t be intimidated. People are more than capable of planting trees and caring for them,” Blustein said. “The benefits of planting a tree are pretty amazing for climate and cooling purposes and for providing habitat.”

Resources

* American Horticultural Society, ahsgardening.org

* Northwest Horticultural Society, northwest.org

* Pacific Northwest Chapter of the International Society of Arboriculture, pnwisa.org