Arbor Day, Plant for Diversity

As an arborist, trees are my favorite plants. And there is a holiday to celebrate my beloved trees, Arbor Day. Arbor Day is celebrated on the last Friday of April every year in Nebraska. This year that falls on April 24th. This holiday is not the same throughout the United States, it is moved around for other states to be in the best planting time for the year for each state that celebrates it.


Deciding what tree to plant is very important and sometimes difficult. Diversity is key when choosing your tree. The general rule is to plant no more than 10% of a tree species, no more than 20% of a tree genus, and no more than 30% of a tree family in a respective urban area.

Diversity has not always been used as widely as today, and we have learned from that. In the early 1900’s American Chestnut trees were wiped out by Chestnut blight. We replaced many of those trees with American Elm trees which were then destroyed by Dutch Elm disease in the 1960’s. Those were then replaced with Ash trees which are now being demolished by Emerald Ash Borer. Also, in the early 2000’s we lost a majority of our windbreaks to Pine Wilt disease.

Diversity of our tree species helps reduce the problems from widespread disease and insect outbreaks. Look around at what types of trees you have and what types of trees your neighbors have before deciding on a new tree, try to avoid over-planting the same few trees throughout the neighborhood. Plus, diversity of trees is more aesthetically pleasing because of the different leaf and bark textures, different bloom times, and overall differences in trees.

Using understory trees

There are many trees that make a great understory trees and can be planted in the shade and protection of larger trees. Those trees would include things like redbud, pawpaw, and some of our dogwoods including flowering or Kousa dogwood. These trees prefer to have part shade so under a larger tree is a great spot for them. This can help mimic nature and help the overall growth of both the understory tree and larger tree.

Care of Trees

Keep newly planted trees well-watered. Always water newly planted trees, shrubs, or any other plant immediately after planting. Trees should be watered every 10-14 days throughout the growing season and even some during the winter on warmer days. Each watering should give the tree 1-2 inches of water. The best way to determine if a tree needs to be watered is to insert a soil probe or 12-inch-long screwdriver into the ground around the tree. If it goes in easily there is no need to water, if it is difficult at any point then water is necessary for the tree.

A mulch ring should be established and maintained around every tree. Mulch helps to keep the roots cool in the summer and regulated to a uniform temperature through the winter. Mulch will also help keep weeds down and reduce competition of water and nutrients from turf and other plants. Mulch also reduces damage to the trunk of trees from lawn mowers and trimmers. Finally, organic mulch is a way to hold moisture for use later by the tree. Mulch rings should be only 2-3 inches deep and in a circle around the tree at least 2-3 feet out. Organic mulches are a better choice than inorganic mulches. This mulch will need to be renewed every year to maintain an effective layer because it will break down over the growing season which will improve the soil.

Tree Selection and Pruning

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Arbor Day is Friday, April 28th, 2017. Arbor Day is always an exciting day for me because I really appreciate trees and understand the real potential that can come from planting a tree. With Pine Wilt and the concerns of Emerald Ash Borer creeping closer it seems there is always a need to plant a tree, if not for you, then for future generations.

There are a lot of good trees to plant when you do plant a tree. The most important thing to remember when planting trees, is Diversity. When you go to purchase your tree, look around your yard and even your neighborhood. Try to avoid planting multiple trees of the same species, genus, or family of plants in the neighborhood and in your own landscape. You may enjoy Maples, but you want to make sure you plant other types of trees in your yard besides just maples to help avoid an issue that may arise should another pest come through like what we saw with Dutch Elm Disease or Chestnut Blight or now Emerald Ash Borer.

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Each year, ReTree Nebraska comes out with a new diverse list of trees that grow well in Nebraska and are often under-utilized. That list includes Baldcypress, Catalpa, Kentucky Coffeetree, Elm Hybrids, Hackberry, American Linden, Sugar Maple, Chinkapin Oak, Bur Oak, English Oak, Sycamore, Shantung Maple, Miyabe Maple, Gample Oak, Tree Lilac, Concolor Fir, Black Hills Spruce, and Ponderosa Pine. In 2017, ReTree Nebraska added Turkish Filbert including other nut trees such as Hickory, Chestnut, Pecan, Buckeye, and Walnut to the list of good trees to plant in Nebraska. There are a lot of other great trees to use in your landscape, this is just a short list.

Turkish Filbert is a unique, under-utilized tree in Nebraska. It grows up to 40-50 feet tall and 30-50 feet wide. It has large, bright green leaves that turn yellow in the fall. This tree has catkin flowers, like a cottonwood.  It has edible nuts that are produced in a cluster of 3-6 and have a spiny husk that covers the nuts. Often squirrels eat the nuts, but they can be roasted and eaten by humans. This tree is most commonly used as a shade tree or a specimen tree in a landscape.

Another thing to think about with our young trees, is pruning. Eric Berg, a community forester from the Nebraska Forest Service wrote a great article on pruning young trees. We need to start pruning our trees when they are young to minimize tree wounding and cause the trees to grow stronger, mature growth. A tree planted in a landscape setting, rather than being planted in a forested area, will grow out more than up and not develop a strong central leader. Often our trees develop multiple leaders that lead to weak growth that can easily be broken in storms. We saw the damage from weak branch attachments and poor growth in our ice storm this past winter.

pruning tools-K. Todd
Photo courtesy of Kim Todd, UNL Department of Agronomy and Horticulture

We can prune a tree when it is young to help prevent some damage in future storms. If you would like to learn more about pruning young trees, Graham Herbst, from the Nebraska Forest Service, will be in Beatrice to teach us about pruning young trees on Monday, June 19th from 6-8 pm starting at the Gage County Extension Office. He will cover how to set pruning objectives, determining a pruning cycle and dose, strategies for specific trees, and how to execute your plan with proper cuts. There will also be a hands-on pruning demonstration at the end of the classroom portion. If you are interested in this program, please call the Gage County Extension Office at 402-223-1384 to sign up.

Arbor Day, Plant a Tree

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Arbor Day is April 24, 2015. To show support for Arbor Day, we should all go out and plant at least one tree. If you don’t have room for one in your yard, trees can be donated to parks and schools or you can go to the Arbor Day Foundation and donate a tree to be planted in one of our Nation’s forests. Nebraska didn’t always have as many trees in it as it does today, so take some time on Arbor Day to plant a tree to ensure that we have trees for years to come.

Deciding what tree to plant is half of the battle when planting a tree. There are so many great tree selections that will grow very well in our Nebraska Environment. ReTree Nebraska is an affiliate of the University of Nebraska-Lincoln that focuses on “raising public awareness of the value of trees and reverse the decline and improve the sustainability of community trees and forests”. ReTree has been working on a list of great trees for Nebraska, each year adding more trees to that list. The list for 2015 includes Hackberry, Sycamore, Baldcypress, Catalpa, Kentucky Coffeetree, Elm Hybrids, Hackberry, Sugar and Bigtooth Maple, Chinkapin Oak, Bur Oak, English Oak, Shantung Maple, Miyabe Maple, Gambel Oak, Tree Lilac, Concolor Fir, Black Hills Spruce, and Ponderosa Pine. Any of these would be great choices for your yard, but diversity is the key when planting trees. The 2 trees added to the list for 2015 were Hackberry and Sycamore.

Image Courtesy of Steven Katovich, USDA Forest Service,
Hackberry Tree Image Courtesy of Steven Katovich, USDA Forest Service,

Hackberry is a great tree for Nebraska because it is regionally native and adapted to our ever-changing Nebraska environment. The leaves have an uneven base and typically are found with a gall on the leaves due to the Hackberry psyllid. These galls are not harmful to the tree, they are just an aesthetic nuisance. It is a great tree for pollinators as well.

Image Courtesy of Richard Webb, Self-employed horticulurist,
Sycamore Bark Image Courtesy of Richard Webb, Self-employed horticulurist,

Sycamore is another great tree. Sycamore trees grow very large, up to 100 feet tall with a massive trunk. The leaves on a sycamore tree are tri-lobed and are 4-10 inches long and slightly wider than they are long. Sycamore trees have unique camouflage bark that opens up to a white base.

Another very important factor that you need to keep in mind when planting trees, would include how to plant a tree correctly to ensure healthy growth. First of all, remove all of the burlap and any other materials from the root ball before planting. Be sure to also remove any tags, twine, or wire from the tree. Remember to remove all the grass and weeds that are within the area you will be planting the tree. Dig a hole that is 2-3 times wider and no deeper than the root ball and loosen up the sides of the hole. Plant the tree so that root flare is at the soil surface. Do not amend the soil that is in the hole, backfill with the existing soil. Make sure that the entire root ball is covered with soil to avoid drying out. Add a mulch ring at least two to three feet out from the base of the tree and only 2-3 inches deep.

Staking a tree is not a mandatory practice. If you do have to stake the tree due to high winds, make sure that the tree has plenty of movement to allow it to build stronger roots. Also be sure that the staking material is removed after the first year to avoid the tree being damaged by the staking materials.

Tree Planting: Happy Arbor Day, April 25th

2013-05-09 10.12.49The last Friday in April is Arbor Day. This year that holiday falls on April 25th. In support of this holiday we should all go out and plant a tree or more than one if you desire, or support an organization that does plant trees if you have no need or space for extra trees in your yard.

When planting trees, utilize diversity. Diversity is planting many different types of trees in an area so that if any new disease or insect comes, it doesn’t wipe out all of our trees. The lack of diversity has been a problem recently with pine wilt in Nebraska. Entire windbreaks are being destroyed in a matter of a couple of years due to pine wilt. Just make sure that whatever tree you choose, is resistant to many of the common diseases we see in Nebraska such as Pine wilt.

Planting a tree correctly initially will ensure its success.  Here are the steps to planting a tree correctly:

  • Pick a good location
    • Plant your tree away from buildings and other plants
    • Allow it to grow into the location
  • Dig a hole that is 2-3 times wider than the root ball and only as deep as the root ball
  • Loosen up the sides of the hole
  • Before planting the tree, remove the burlap and wire basket
  • Be sure to also remove any tags, twine, or wire from the tree
  • Do not amend the soil that covers the root ball after it is placed into the hole
  • Plant the tree so that root flare is at the soil surface
  • Install a mulch ring around the tree
    • At least two to three feet out from the base of the tree
    • Only 2-3 inches deep
  • Staking a tree is not a mandatory practice, if you do have to stake the tree due to high winds, make sure that the tree has plenty of movement within the stakes
    • Also be sure that the staking material is removed after the first year to avoid the tree being damaged by the staking materials.
This is a very nicely installed mulch ring!
This is a very nicely installed mulch ring!

One problem that you might notice now in your landscape, after the winter, is deer damage to your trees and shrubs. Deer can do a lot of damage to a tree over the fall and winter months, especially to a smaller or younger tree. Many bucks will rub on trees later in the fall to remove the velvet from their antlers, which can leave a canker or open area on the tree. They can also do damage to our trees and shrubs when they feed on the buds, leaves, and stems of many different ornamental plants. These twigs are going to have a jagged or torn appearance to them due to the way the deer feed on the plants. Typically the damage from deer to a tree can heal, but it will be a location in the tree or shrub where diseases and insects can enter the plant.

My beautiful picture

If you notice deer damage to your plants, there is nothing you can do for the tree after the damage has already happened. However, depending on the severity, your tree will probably survive after being damaged by deer. You can help reduce the problem in the future by utilizing an electric fence around your property to keep deer out of your lawn, or by putting up a 4 foot tall fence around each tree in your landscape. Remember to protect any newly planted tree from deer when planting.