Trees

July: Butterfly Weed

Butterfly weed has a PR problem, because if all you hear is its name, the weed part is a bit of a turnoff. But it‘s a gorgeous addition to any perennial garden, and pollinators absolutely love it. It’s a tough plant too, which makes it a favorite for rain gardens, bioswales, and low-maintenance, natural style perennial borders.

Photo by Maria Gulley

Photo by Maria Gulley

milkweed-112338_1280.jpg

Brilliant orange flowers in huge clusters up to nine inches across bloom from the center out in July. The stems below the flowers can be a bit bare and thin, so it’s a good middle-layer plant rather than something you plant right at the edge of a bed. You may know butterfly weed best as the monarch butterfly plant - plants in this genus are the only food source for monarch caterpillars. With fewer and fewer wild places where butterfly weed can grow naturally, bringing these plants into our yards is vital to keeping the gorgeous orange butterflies around.

Common Name: Butterfly Weed, Milkweed

Scientific Name: Asclepias tuberosa

Light: full sun

Size: 18-30” tall, 18-24” wide

Bloom Time and Color: large clusters of bright orange flowers in mid-summer

Notable Varieties: ‘Hello Yellow’ (somewhat compact yellow-flowering variety); Swamp Milkweed, a water-loving, pink-flowering cousin, has similar flowers in a different color and is also landscape-friendly

Soil: tolerates clay soil and dry soil

Other Notes: pollinator-friendly, larval host for monarch butterflies, native to Indiana, deer resistant, interesting fall seed pods

See other plants of the month.



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Proper Tree Pruning: Art & Science

It's time for another tree care lesson! If you need a refresher on why we value trees so much, check out our post on the top 10 benefits of urban trees. Today we'll talk about proper pruning technique and why it's so important. The tree you see above has completely closed off some cuts and is working on others with even, donut-shaped callus growing over the wound. That's what you want to see, but getting that result is harder than you might think.

If you've ever needed to prune a tree branch and you haven't been trained on the best methods, chances are you've done one of two things: cut the branch somewhere in the middle to meet whatever clearance needs you're trying to achieve, or cut the branch off flush with the trunk. Both of these are bad for the tree. Trees can't heal wounds in the way people heal cuts on their skin. The tree has to grow new bark from the areas around the cut to seal off the damage, and some parts of the tree are better at this than others. When you cut a branch in the middle, the bark just below that wound can't wrap around and seal off the cut, so instead the branch just dies back to a spot lower down the branch where it can seal itself off, and you're left with a stub that will die. If you cut the branch flush with the trunk, you're creating a much larger wound that provides a bigger area for insects and disease to invade, and it takes longer for the tree to seal it off. The tree pictured above has been pruned properly, and you can see that new bark has totally covered the cuts over the years. Learn how to get these results below.

So where should you make a cut? There's a sweet spot at the base of a branch just before where it connects to another limb or to the trunk. There is a ridge of bark on the top of the branch and a little bump called the branch collar on the bottom. Your goal is to cut just on the outside of these two structure. See the diagram on the right for clarification (click to see larger). It won't always be easy to spot the branch collar on the bottom, so if you aren't sure make your best guess. The angle of the cut should follow the angle of an imaginary line connecting the bark ridge and branch collar. If you're having trouble finding the branch collar, make the angle match the angle of the bark ridge as it extends into the trunk.

Step 1: cut a notch (red arrow) on the underside of the branch about a third of the way through

Step 1: cut a notch (red arrow) on the underside of the branch about a third of the way through

Step 2: cut the branch all the way through at least 4-6” past the notch (red arrow) you cut in step 1

Step 2: cut the branch all the way through at least 4-6” past the notch (red arrow) you cut in step 1

Step 3: make your final cut just outside the bark ridge (red arrow) at an angle away from the tree

Step 3: make your final cut just outside the bark ridge (red arrow) at an angle away from the tree

If you look at a branch that has broken off in a storm, you will sometimes notice that the weight of the falling branch caused a strip of bark to rip off of the trunk as it fell. This can also happen when a branch breaks as you work on sawing through it, and ripping bark like that leaves a wound that can be difficult for a tree to heal over. If you are removing a branch larger than 1" in diameter, you need to use the three cut technique to avoid tearing the bark. First you make a cut on the bottom of the branch further up than where your ideal cutting zone is. This cut should go about a third of the way into the branch. Next, you cut off the branch on the outside of this pre-cut. If the bark starts to rip, it will stop when it gets to your first cut. Your third cut should be at the base of the branch in the sweet spot we discussed above.

Congratulations! You now know how to prune your trees to keep them happy and healthy for years to come! Please spread your knowledge, and never hesitate to ask a professional for help if you have questions. If you’re more of a visual learner, here’s short video that shows how to cut medium-sized branches and shows where you want the finishing cut for any size of branch. For more details written instructions, you can also check out this Purdue Extension bulletin about pruning trees and shrubs.


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June: Tulip Tree

Tulip tree, also known as tulip poplar is Indiana’s state tree. It’s also an attractive, landscape-friendly shade tree that grows at a decent pace and is native to Indiana. Plus it has cool-looking flowers that are a huge hit with bumblebees! It’s a winner all around, as long as you have the space and sun it needs.

Tulip tree became the Indiana state tree in 1931. It was selected for its stately size and form and because it can be found all over the state in mature forests. Tulip trees can become truly massive with trunks over 4’ across. The record-holder for Indiana has a trunk diameter of 280”, or nearly 7.5’ in diameter, and is over 100’ tall. Native Americans used the large trunks to make dugout canoes, and the wood is sometimes used to build furniture today. While tulip trees don’t have many serious pest or disease problems, when they’re under stress they can become susceptible to aphids and tulip tree scale. If you see sticky residue on leaves or on the ground under the tree, take a look at younger stems for tan lumps or aphids, and contact a tree care professional or landscape company with tree experience for diagnosis and treatment.

Common Name: Tulip Tree or Tulip Poplar

Scientific Name: Liriodendron tulipifera

Light: full sun

Size: 60-90’ tall, 30-50’ wide

Bloom Time and Color: green tulip-shaped flowers with cream and orange markings in early summer

Notable Varieties: ‘Majestic Beauty’ (variegated leaves with chartreuse margins

Soil: tolerates clay soil

Other Notes: good golden-yellow fall color, pyramidal form, native to Indiana

See other plants of the month.


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Top 10 Benefits of Urban Trees

Street trees in Rome Photo by Maria Gulley

Street trees in Rome
Photo by Maria Gulley

Many people enjoy looking at trees, using photos of them as desktop backgrounds, or even occasionally planting one on Arbor Day (or when Keep Indianapolis Beautiful hosts a community tree planting in your neighborhood). While the general opinion is in favor of trees, we are sometimes hesitant to have them in urban or suburban settings near our homes and streets because we're intimidated by the damage they can cause or the effort they can require to maintain. In reality, a properly chosen and placed tree requires little maintenance after establishment, and as long as that maintenance is attended to, the chances of a tree crashing down on your house without warning are low. But over and above that, urban trees are important because they provide tremendous (I could have said "tree-mendous" but I stopped myself) benefits to our environment, communities, health, and even economy. Below are the top 10 benefits of urban trees from as ranked by David Nowak at the U.S. Forest Service and presented by the staff at Keep Indianapolis Beautiful.

1. Oxygen Production
If oxygen is so important, why are we placing this benefit at the bottom of the list? Trees do produce oxygen, but the amount produced by urban trees isn't much compared to the amount produced by the oceans and forests of the world, and that oxygen does a pretty good job of working its way through the atmosphere to areas far from oceans and large forests.

2. Noise Reduction and Screening
Trees can buffer the noise from a busy road or highway or help create a quiet spot in a city. Not only can the trees physically reduce some of the sound, but they also mask unpleasant sounds with their own soothing noises of rustling leaves and birdsong.

Trees along the Cultural Trail in downtown Indy Photo by Maria Gulley

Trees along the Cultural Trail in downtown Indy
Photo by Maria Gulley

3. Wildlife Habitat
Without trees, you can't establish much wildlife. Wildlife provides opportunities for informal education and nurturing curiosity, and it is essential to our urban ecosystem. Native trees are especially valuable, as a single species can host literally hundreds of species of native insects that in turn feed birds and other animals. In a few weeks I'll be writing about the value of native wildlife and biodiversity, so tune in for an exciting discussion.

4. UV Radiation Protection
A tree's shade can reduce UV exposure and delay sunburn. The benefit will vary depending on the density and spread of the canopy, but dense shade can offer up to a 95% reduction in UV radiation.

5. Greenhouse Gas Reduction
Trees use the carbon dioxide in the air to make the sugars they need to live, and this helps offset the carbon dioxide we produce both biologically and through burning fossil fuels. In one year, an acre of trees can consume enough carbon dioxide to match what is emitted by an average car driving 26,000 miles. Our urban forests aren't large enough to totally compensate for the amount of carbon dioxide we produce, but they certainly reduce it.

6. Air Quality Improvement
Producing oxygen and capturing carbon dioxide are types of air quality improvement, but urban trees don't stop there. They can also reduce air pollution as the trees catch particulate matter in the air that might otherwise turn into unhealthy smog.

7. Water Quality Improvement
Whenever we get a heavy rain in Indianapolis, we are at risk for a combined sewer overflow. What this means is that so much rain is running off of our paved surfaces and into our sewer system that raw sewage overflows and gets into our natural waterways (see the diagramon the left). Trees can reduce the number and severity of combined sewer overflows by collecting rain on leaves, bark, and in the soil. Indianapolis is doing great work in using green infrastructure to manage stormwater, and was even featured in a 2013 report from the Natural Resource Defense Council, but there is still a long way to go.

8. Health Benefits
Beyond reducing UV radiation, trees offer some surprising and substantial health benefits. Trees reduce asthma and respiratory disease by reducing air pollution. Being around trees and other plants can have psychological effects similar to antidepressants and ADD medication, and they have been shown to reduce stress. Hospital patients with a view of greenery recover faster, require less pain medication, and have fewer complications than patients without such a view.

9. Aesthetic and Socio-Economic Benefits
We intuitively understand the aesthetic benefits of trees. They're beautiful, and they make the spaces around them more beautiful. The socio-economic benefits of trees are less obvious, but studies show that trees reduce crime rates, increase business sales, and reduce traffic speeds, and we also know that they increase property values and strengthen communities.

Street trees in NYC Photo retrieved from Pixabay

Street trees in NYC
Photo retrieved from Pixabay

10. Cooling and Energy Savings
Not all of these benefits can be measured in dollars and cents, but this one can. Trees reduce heating costs through shade and evapotranspiration (as they pull water from the soil, more evaporates from the leaves and has a cooling effect), or they can provide a windbreak to reduce winter heating if properly placed. Adding greenery to cities can reduce or even eliminate the urban heat island effect. The urban heat island effect explains that urban areas tend to be substantially warmer than suburban or rural areas due to the lack of green space and the abundance of heat reflecting surfaces like glass and asphalt.
 

These 10 are by no means the only benefits of urban trees, and many of these could be broken down into several separate benefits, but this gives a glimpse about just how essential trees are in our communities. If you want some handy pamphlets summarizing some of these benefits, I highly recommend these fact sheets produced in collaboration by the Indiana DNR Community and Urban Forestry program and the Indiana Urban Forest Council. To delve into the tree benefits we can put a price tag on, check out the free i-Tree Design tool to calculate the value added by any tree. We don't need to be afraid of trees; we need to embrace them and the benefits they provide. What are some of the reasons you love trees? Can you think of any benefits I left off the list? Feel free to add to the conversation in the comments.


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May: Bluestar

There are a lot of perennials that I think deserve more attention. Bluestar is definitely one of them. This plant has an informal but not messy look, blooms earlier than most perennials, stays put where it’s planted, and has brilliantly golden fall color.

There are a handful of species in the genus Amsonia referred to as bluestar that grow naturally in different regions of the U.S. The two that are easiest to find for sale in the Midwest are Amsonia hubrichtii and Amsonia tabernaemontana, and A. tabernaemontana is also native to our region. They all have in common clusters of pale blue flowers and yellow fall color. The main difference is in foliage texture: A. hubrichtii has an airy, fine texture while A. tabernaemontana has a more substantial presence with wider leaves. They are good for massing in mixed perennials beds, and pollinators love the late spring flowers.

Common Name: Bluestar

Scientific Name: Amsonia species, hybrids, and varieties

Light: full sun

Size: 2-3’ tall and wide

Bloom Time and Color: pale blue flowers in May

Notable Varieties: ‘Blue Ice’ (dwarf variety of A. tabernaemontana), ‘Storm Cloud’ (variety of A. tabernaemontana with smoky purple stems and emerging foliage and deeper blue flowers)

Soil: doesn’t like waterlogged soil, but can take a lot of water if it drains quickly

Other Notes: native to Indiana, deer resistant, pollinator-friendly, good fall color

See other plants of the month.


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April: Flowering Dogwood

April: Flowering Dogwood

If you ask someone what their favorite tree is, there’s good chance that they will name a spring-flowering beauty. And of those spring bloomers, flowering dogwood is a classic crowd-pleaser. With its snowy white or soft pink blossoms, flowering dogwood stands as a sign that spring has fully arrived at last.

Keep Pollinators Around All Season Long

Keep Pollinators Around All Season Long

If you’ve been following our blog for a while, you have probably picked up on the fact that I’m a big fan of pollinator-friendly landscaping. Pollinators like bees, butterflies, moths, and hummingbirds are responsible for reproduction in many of our favorite landscape and food plants, and they’re fun to watch. Nothing says “summer” to me like watching a garden buzzing with all kinds of pollinators. But summer isn’t the only season these critters are out and about, and one of the keys to ensuring that they maintain healthy populations is to make sure that we’re planting pollinator-friendly plants for the full season.

Salt Tolerant Plants

Salt Tolerant Plants

While we haven’t had a lot of huge snow events this year, almost every week there’s enough of a risk of snow or ice to put down road salt at least once. Over time, this salt can splash onto parking lot and roadside plants enough to damage the foliage, or temporarily shock the soil with too much salt for the plant roots. Salt draws water out of plant cells and leaves them looking burnt and stunted. In cases of soil salt accumulation, sometimes it just looks like a plant is smaller and struggling compared to the same plant a few feet further back from the street.

February: Sycamore

February: Sycamore

Sycamore trees are among the most distinctive trees in the American landscape. Whether you know the name or not, you have no doubt noticed beautifully mottled gray and tan and white bark on a giant of a tree in a park or a forest or driving along the highway. For me, it was one of the first trees I learned to identify growing up as a budding plant nerd.

January: Serbian Spruce

January: Serbian Spruce

For a dense evergreen tree in a classic Christmas tree shape, Serbian spruce is the best fit for central Indiana. The needles have thin white stripes that give the tree a faint white-ish cast from a distance for a softer look. They work well as focal points, or in groups to form a living barrier.