Caring for Climate Trees in Eugene

Some climate trees can need a little extra TLC

We pay extra attention to all of our trees during their first few years of establishment. Watering, mulching, pruning, inspection, restaking, vandalism repair —this little bit of extra work has a huge impact on the tree’s success in the long run. Over the last decade, the Eugene Branch has been integrating more climate resilient trees into its planting regimen. They’ve found that these trees need a bit more attention, but because these trees will stand up to the changing climate, it’s definitely worth it.

Because these trees are not widely used in the nursery trade, they have not been selected for form in the same way. One guideline of climate change is that by 2050, each area’s climate will become like that of the area 500-700 miles south of them, so many of the trees we are trying are native to the area south of Eugene. Because of how they’ve been selected, more common trees in the nursery trade are more uniform—they tend to have trunks that go straight up and branches that are well-spaced.

Many common trees are cultivars, often patented clones. Of course, these trees still require some pruning, but they have had years of effort to select for form, so they are as predictable as a fast food burger. This process diminishes intraspecific diversity, or the diversity within a species, something that is just as valuable as interspecific diversity, the diversity between multiple species.

Some of the climate resilient trees the Eugene team are working on—like valley oak, blue oak, and California live oaks—often exhibit rapid, explosive growth, sometimes taking on a “rangy” or “shrubby” appearance. During their first three years of growing, they need more pruning and staking attention to achieve a good form.

“These climate trees need about twice as much pruning as a typical tree during their establishment years,” says Eugene Director Erik Burke. “But they are very drought tolerant and tough, and that gives them a leg up in the face of the changing climate.”

The Eugene Branch is about to start its yearly pruning. One reason that Eugene prunes in late summer, rather than in the dormant season, is that it slows the trees down.

“Here, fast growth is a bigger issue than slow growth,” Erik says. Fast growing trees are tougher to manage for strength and stability, and will often have weaker wood more prone to failure, particularly in snow or ice storms, which is something you don’t want in the urban environment.

It’s because our trees are in the urban environment that it’s so important to prune them to have a central leader and stong structure. A tree in the forest or a field will prune itself. But in the urban environment, we want to prune trees before a truck does, which could seriously damage the tree, or before a storm does, which would pose a threat to people and property.

The benefits of any one tree grow exponentially with every year it’s alive. We want our trees to have long, healthy lives so they can provide shade, clean air, and habitat.

“Climate resilient trees are only becoming more and more important, so we think they are worth that bit of extra effort,” Erik says.

Leaflet: Spring Tree Care

Spring has Sprung – What that means for your trees

Trees are breaking dormancy, but that doesn’t look the same for every species. Some are early risers, and some sleep in. A bunch of factors go into it, including species, daylight, and temperature. Here are some things you can do to take care of your trees this time of year.

Mulch Madness

It’s a great time to refresh mulch as needed. The objective is to mulch the tips of the roots as they grow outward from the base of the trunk. They will grow into soil that’s moderate in temperature and contains moisture, factors that mulch will provide. Because the roots are growing outward, when you mulch trees in their second year in the ground, aim for more of a 4-5′ diameter ring of mulch, still 3” thick, about a foot from the base of the trunk.

You may have noticed that some trees hold their leaves through winter. They’re called marcescent leaves, and they are a sign of last season’s growth. You’ll see them on native oaks like Oregon white oak (Quercus garryana) and scarlet oaks (Quercus coccinea). Come spring time’s flush, these leaves will be shed to make room for new growth. You can use these leaves as mulch!

Go easy on the pruning

It’s best to go easy with regard to pruning during “bud break.” This is when sap is rising up the tree, after having dropped to the roots in the fall. As the sap is rising, some trees (maples, for example) will “bleed” if pruned as sap is rising. It’s not harmful to the tree—that’s where maple syrup comes from, after all—but it can be disconcerting to see.

Weekly Watering

It’s almost time to start weekly watering for newly planted trees. “Deep and infrequent” is the recipe for success. Starting mid-April, 15 gallons all at once, once a week is ideal. Either a gator bag, hose on a gentle trickle for maybe 20 minutes, or a 5-gallon bucket with three 1/8″ holes drilled on the side at the bottom and filled 2-3 times consecutively works great.

If the temperature gets over 90 degrees, bump that up to twice a week. If we see another heat “event” coming, a good, deep soak beforehand is very wise as preventative medicine.

More tree care here!

Leaflet: Prepare Your Trees For Winter

Pruning techniques to make your trees more resilient to winter storms

The temperatures have dropped, and it’s probably just a matter of time before we get some serious winter weather. The best thing we can be doing this time of year to make our trees more storm resilient is pruning. We’re going to walk you through the pruning techniques that will help a tree if and when we get another serious winter storm. 

As we’ve seen more and more in recent winters, the combination of wind and ice will lead to branch failure—in short, nature prunes itself. That’s exactly why it’s best to prune problem areas now rather than waiting until snow and ice is predicted. Ice can increase the weight load on a branch by up to 30 times.

For an even more in-depth guide to pruning, visit our pruning page.

Prune outside the branch collar. The most important technique when pruning any branch, whether it’s a quarter-inch or four inches diameter, is to prune just outside the branch collar. On some types of tree, the branch collar is obvious. It is that bit of swelling—like a collar—at the base of where the branch connects to the trunk. That swelling is an accumulation of healing hormones. If you cut flush against the trunk, you’re cutting away the hormones that will close it off and protect it from pests and diseases.  

Remove the Ds. The best way to start is to look for branches that are dead, diseased, dying, or decaying— anything that starts with a D. Just take a nice pruning saw or or some hand pruners and prune that right out of the tree.

A small six- or seven-inch folding saw is really all that a homeowner needs. We could do 99% of what we end up doing with just hand pruners and a folding saw on a young tree.

Mind your pruning budget. You shouldn’t prune away more than 25% of your tree’s canopy. Leaves are effectively solar panels that produce energy for the tree, and you don’t want to remove too much of that. Sometimes people want to prune their trees to encourage it to grow taller, and they’ll prune all the lower branches and make a sort of lollipop. So another part of calculation is that two-thirds of the trunk needs to have lateral branches.

Dead and dying branches do not count toward that budget, because they are not producing energy for the tree. The tree wants to lose those anyway and, as we already mentioned, nature will more recklessly prune them away during the next storm if you don’t. Suckers—the small branches at the base of the trees—should also be removed. While they do have leaves, they also do not count toward that budget, because they could become so vigorous that they just take over. 

Look for included bark. A wide angle between a lateral branch and the trunk creates better architecture than a sharper angle. When the angle is more acute, the bark will start to fold over itself in the crease at the connection point. This is called included bark. Branches with included bark are where more than 80% of failures happen.

There might be instances where pruning all the branches with included bark will take you beyond your pruning budget, in trees like Japanese maples, zelkova trees, or columnar (upright) cultivated varieties. There are ways to address included branches without removing them entirely. You can cut away the most vigorous upright branches along the branch, which will stop that branch from growing more. There is a gravity-fed hormone in upright branches that encourages growth. By removing the upright branches, you change the hormones to those for repair and reproduction and in doing so, slow the growth of the branch relative to the trunk.

Encourage a strong central trunk. We’re trying to prune trees to have a strong central trunk—or central leader. Some trees, like conifers, grow a central trunk naturally. Other trees want to have a more rounded canopy. We want to create a strong backbone so that a tree is more resilient to wind. It is a bit unnatural, but when we are planting trees in the built environment, we have safety considerations to keep in mind. If a tree is in the middle of a giant backyard, it can take a more natural shape, but if it’s somewhere where its branches could fall on a house or a car, it’s helpful to have that strong central trunk.

When you prune, look for a strong central leader on a young tree that can be encouraged as it matures, and prune away competitive side branches. The rule of thumb is that you don’t want to have any lateral branches that are more than half the diameter of the central leader. By keeping those side branches smaller, if they fail, it’s less likely to be catastrophic to the tree or its surroundings.

If a storm comes!

When a winter storm does arrive, what do you do?  Shake off snow, but not ice. Light snow can be gently shaken from branches with a broom moved in an upward motion. Heavier snow and ice should be allowed to completely melt  because branches with ice especially often fail when shaken.

Once the snow is gone, inspect your tree for damage, taking care to take safety precautions as necessary. You can use a pruning saw to cut away any dead or damaged branches at the nearest branch collar.

Pruning resources:

  • We have an entire webpage on how to prune that gets into even deeper detail.
  • If you have a bigger tree, and the task of pruning it is beyond you, get in touch with one of these recommended arborists.
  • If you have a specific question that you just can’t crack, you can write our new email address for pruning questions: [email protected]


Get to Know our pruning program – 2,000 trees pruned this season!

Pruning trees contributes to a more equitable community. Or, more accurately, pruning trees at no cost contributes to a more equitable, livable community.

 How? We’ve learned that a major barrier to many households getting a street tree is the cost of maintaining the tree. Pruning can be very expensive, and it gets more expensive as the tree ages and grows if problems are not addressed early. Properly pruning a tree when young is an excellent investment and can delay or even prevent future expenses, making a tree more affordable. Pruning young trees at no cost by trained Friends of Trees volunteers is one important way to help get more trees into more neighborhoods, especially under-served, low-income communities which are often communities of color impacted by systemic disparities.  That is exactly why Friends of Trees is focusing efforts on specifically those communities who will benefit the most.

Our pruning program also benefits youth through our educational partnerships. While we are pruning trees we are also training young people to prune. Through partnerships with organizations like Rosemary Anderson HS POIC, student interns in our pruning program earn an hourly stipend while building valuable job skills. Pruning skills can be developed and honed in preparation for becoming an ISA-certified arborist – a very solid living with excellent job security. Added bonus: Exposing young people to the benefits of trees and tree care contributes to a greater appreciation of trees and nature, helping to grow the next generation’s Tree Team.

Pruning = longer lived, healthier trees = healthier planet + people. The benefits of trees—oxygen creation, pollution and stormwater absorption, healthier humans (DYK that trees help combat cardiac and respiratory ailments and can even contribute to increased birthweights?), and so much more—increase exponentially as trees grow and age. And the earlier a tree is properly pruned, the greater the chance it will grow to a ripe old age benefitting neighborhoods and the planet for generations to come.

Pruning for structure (shape) and clearance (sidewalks and streets) is the primary way to steward and care for a tree post-establishment. Proper pruning contributes to the long-term health of the tree, while lack of pruning, or pruning incorrectly, will contribute to the premature demise of the tree.  Pruning in the built environment (as opposed to a natural setting) is also key to preventing tree-related damage following inclement weather.

There’s another reason pruning young trees is better: It’s easier for the tree to recover from pruning when it’s young than it is when the tree is more mature (trees have to “recover” after any sort of pruning, good or bad, it’s just far more efficient for them to recover from careful “surgery” by a trained pruner as opposed to “natural” pruning by snow/ice + wind). When pruned, a tree immediately gets to work “sealing” the cut, working to close off the wound.

When pruning young trees, we have the opportunity to make a 5-cent cut today to prevent the need for a $100 cut 20 years down the road (or, so the saying kind of goes ;).  Not only is it more cost-effective to properly prune young trees, the larger the pruning cut (because the limbs are larger), the longer it takes the tree to recover. A tree can quickly seal and move beyond a ¼” cut made with hand pruners, but it may takes years to recover from an 8” diameter cut made with a chainsaw (and it may never recover at all). BTW, trees don’t actually “heal,” they seal or compartmentalize and – once recovered – they then grow more vigorously.

With all the benefits of pruning it’s a good thing our pruning program is so popular with volunteers (100+ pruning volunteers every year!), since volunteer-power is the only way we’ll be able to prune 2,000 trees this season. Pruning is especially popular right now as it’s pretty pandemic-resistant: pruning is not a large group activity and it takes place 100% outdoors. In fact, it’s because of COVID that this will be the biggest pruning season yet, with a 40% increase in trees pruned over last season! BTW, we’ll prune any young street tree in our service area (6” diameter or smaller), not just the trees we plant – all at no cost (thanks in large part to our partners at City of Portland Bureau of Environmental Services).

Pruning trees properly contributes to the health of the tree and to those who live under its canopy. We of course want the trees we plant to grow and thrive, and proper pruning when young is key to tree health, so pruning is an important part of our Neighborhood Trees program. Need more information? Visit our tree resources page for more information about tree care and the benefits of trees. Ready for a tree of your own? Get started here!

Photo: Youth interns learning to prune, part of our Rosemary Anderson High School/POIC partnership; August 2020.

Neighborhood Trees Program FAQ

Some of the Why, Where, and What-Have-You of planting trees in the city with Friends of Trees

Since 1989 Friends of Trees has been growing our urban canopy through planting street and yard trees in neighborhoods. A LOT changes during 30 years of tree planting! We continually work with our city and county partners to ensure the right tree is planted in the right place, and since every location is different we are used to getting quite a few questions. Here are answers to some of the questions we get the most:

I want a smaller/larger tree for my planting strip but all the trees on this list are just too big/small, why can’t I get a smaller/larger street tree?
We work closely with our municipal partners and we can only plant trees that are on their approved street tree planting lists. One of the goals of our program, and the partners we work with, is to increase the urban canopy in order to maximize the benefits. In other words, the larger the tree, the more the urban canopy grows, which provides more benefits in terms of cooling in the heat of summer, providing oxygen, and cleaning our air and water. So when a planting site allows it we need to optimize the size of the tree planted, and consequently, maximize the benefits provided. We also want to make sure we aren’t planting trees that are too big, in order to protect existing urban infrastructure. So these same guidelines ensure we aren’t planting over-sized trees in spaces that are too small.

I want to plant a fruit tree in my planting strip and I know you have them, why aren’t they on my list of approved street trees?
Fruit trees are only approved for certain spaces, such as yards or planting strips that are six feet or larger and have overhead primary power lines (however, Vancouver and Clark County do not allow fruit trees to be planted as street trees at all). If you’d like a fruit tree for your yard in addition to your street tree, we offer a wide variety, including apple, pear, plum, fig, and persimmon.

I only want native trees for my street tree and you only have one native on this list, why don’t you plant more natives?
Right Tree Right Place! We love native trees, but many tend to get pretty big and just won’t work in some planting locations due to overhead power lines, if the strip isn’t wide enough, a nearby intersection, etc. We want to make sure your tree is the best tree for your planting spot! We also want to plant as diversely as possible toward a resilient urban forest. P.S. Want to plant some natives? Join one of our Green Space planting events–all natives, all the time.

I want a street tree, but will it break the sidewalk?
Again, Right Tree Right Place! The trees offered by Friends of Trees do not have aggressive root systems and are specially approved to minimize such conflicts. Proper watering also helps. Deep watering for the first three years after planting encourages tree roots to grow deeper in the soil, we recommend 15 gallons a week during the summer for the tree’s first three years, and as needed in the future when temperatures are extreme. Keep in mind that we cannot guarantee that the trees we offer will never buckle sidewalks, as they are living beings and situations vary. We do our best and encourage you to keep an eye on your tree.

I’m concerned that tree roots will damage the sewer pipe, doesn’t this happen?
A tree’s roots grow where the growing is easy, they are opportunistic and not invasive. They do not seek out water or sewer pipes unless the pipes are leaking. Further, 90% of tree roots are in the top 2-3 feet of soil, and most sewer lines are deeper than that. Your municipal tree inspectors take into account the location of your water meter and assigns the planting location within the guidelines of the water company.

Can you help me remove a tree so I can plant a new one with you?
We can’t help you with a tree removal, but you can re-plant with our program if the city allows you to remove your tree. If you want to remove trees in your yard, check with the city to see if there are laws affecting your tree. To remove a street tree, you need a permit. Contact your city’s urban forestry department directly for a removal inspection, a list of contact information for our municipal partners is here. It’s a good idea to request that the city mark “all approved locations.” If you want to re-plant with us after removal please include on your application that you are working with Friends of Trees. Visit our website for more information about tree removal and replacement.

The approved locations where the trees are going are strange, can you change the location?
Unfortunately we can’t change the location. All street tree locations are based on a city inspection, and there are many factors involved, including distance from underground utilities, overhead lights and power lines, utility poles, fire hydrants, intersections, and street signs. Planting in the spot chosen by the inspector will help ensure your street tree has the best shot at surviving–and thriving!