Planting Elm Trees

Summer seems to be here to stay and the house has been warming up.  Shae and I talked again about getting air conditioning (our 1984 unit has never worked since we moved in).  The conversation only took about 5 seconds as we both understood that the choice was to either get AC or pay off the house this year.  The needs have once again trumped the wants.

The cheaper and lengthier option is to plant some shade trees in our yard.  Our yard is very spartan of trees with only a silver maple along the street and an ornamental by the front of the house.  Last fall we planted a Japanese dogwood in the front to replace the neighbors tree that fell over in heavy rains.  We also planted a silver linden in the far backyard.

Yesterday my order of two Princeton American Elm trees arrived in the mail from a nursery in Joplin, Missouri.

Some Tree History

American elm trees were THE street boulevard tree in the United States.  The vase like shape made great cathedral canopies that formed aesthetically pleasing shaded passageways for horse drawn carriages and early automobiles.

Then in the 1920s, disaster struck.  Lumber imported from Europe contained an invasive beetle and the beetle carried spores for a deadly fungus.  The beetles ate the bark from the American elm trees and spread the spores of the fungus from tree to tree.  The fungus would cause necrosis and was the source of what came to be known as Dutch Elm Disease, or DED.  DED wiped out millions of elm trees in America and the once beloved tree that inspired more Elm streets than Main streets was largely forgotten or shunned.

Municipalities, looking for a new streetscape tree to take the place of elms turned to the attractive ash tree.  Of course, you know what happened to ash trees.  Once again an invasive beetle, the emerald ash borer came into the ecosystem and devastated the ash tree population.

For the third time, municipalities had to search for replacement trees to line the streets with.  This time silver maples, ornamental pears, lindens, and oaks were selected.  Each has its own set of problems but so far none has been massacred like the elms and ashes before them.

Then something kind of miraculous happened.  In the 1990s the USDA began research on hybridized elm trees with resistance to DED.  Several new cultivars were developed including, Valley Forge, Jefferson, and New Harmony.  Princeton was an old cultivar that was found to have natural DED resistance and cuttings (clones) of these old surviving trees were propagated after testing well against DED infection.  The USDA testing for DED resistance found that the new cultivars had 86% to up to 95% survival rates (depending on the cultivar) when injected with two to three million spores.  The typical beetle will carry around 100 spores.

Planting Steps

Shae and I measured and staked the locations for the two trees a few days ago.  Princeton elms grow to 60-80′ tall and a crown diameter of 30-40′.  In favorable conditions they can grow 3-6′ a year and can live between 100-300 years.

To plant our new trees, I dug a hole about three times the width of the pot and about the same depth as the pot.  I removed all of the grass and mixed in some potting soil.  The tree should be planted at the same height or slightly higher than the surrounding terrain.  Planting too deep is detrimental to the tree because the roots need oxygen from the surface and the trunk doesn’t like to be covered up with soil or mulch.

Both trees were root bound.  Root binding happens when a tree or shrub outgrows its container size.  The roots will hit the edge of the container and then start circling around.  The best way to deal with root bound plants is to cut an X in the bottom and four vertical slits on the sides to free up the roots.  If the roots aren’t freed and pointed outwards, they will continue to grow around in circles and eventually strangle themselves.

I finished up the planting by adding a layer of triple shredded hardwood bark mulch to help keep moisture from evaporating.  I also added a plastic guard to protect the trunk from animals, little boys, and the lawn mower.  The mulch should not be touching the trunk and the sapling trees will need daily watering for the first couple of months until their roots are established.

Additional Care

Like a small human child, elm trees need the most care in the first 5-10 years of their lives.  Annual pruning to develop a strong central leader (trunk) is recommended to keep the iconic vase like shape that elms are known for.  Pruning should be done in the early spring or late fall when the tree is dormant.  Bugs are not active yet and the risk of infection is lower at these times.

Conclusion

If all goes well, these trees should grow to be about 25-30 feet tall in 8-10 years.  That should provide us with a nice shady backyard and a cooler house.  Even if we have installed a new AC unit, we should still benefit with lower electricity bills because of the added shade.