Wednesday, August 5, 2015

Choosing Good City Trees for the Midwest

Trees have many benefits, detailed throughout this blog.  They reduce stress, reduce flooding and erosion, and increase rainfall, to name but three lesser known qualities.  However, choosing the correct trees ensures happiness with your (or your organization's) investment.  Below we have our recommendations for excellent city trees to grow in the Midwest, the area we define as between the Appalachians in the east and edge of the Great Plains in the west.

Our first and probably favorite choice is the Thornless Honeylocust (Gleditsia triancanthos form inermis).  This tree has it all.  It is fast growing, very drought tolerant, and has a downward pointing root system (meaning it generally won't buckle sidewalks with shallow, sideways spreading roots).  It grows in zones 3-9, We generally recommend buying these trees as smaller (and much more affordable) saplings from the Arbor Day Foundation and planting them with the Groasis Waterboxx PlantCocoon to ensure adequate water during the first year.

A airy Thornless Honeylocust providing shade for a picnic table along a well maintained walkway.  This path is actually a converted rail line called the B-Line Trail.

Bald Cypress (Taxodium distichum) is an incredible tree, tolerant of city pollution and many adverse conditions.  This tree is something of a contradiction, a deciduous evergreen that loses its light needles in the fall.  This is the famous tree of the Louisiana swamps, which grows broad "knees" when planted in swampy conditions.  However, it can grow far north of its original habitat (in zones 4-10), especially if planted with the Waterboxx PlantCocoon.  Although slow growing, it can grow up to 70 feet high as seen below, but looks verdant, light and airy within a few years of planting. It tolerates swampy conditions well making it well suited for planting along river greenways.  These trees are also drought tolerant.  It can be purchased here.

Mature Bald Cypress in the background, with a more recently planted Bald Cypress in the foreground.  We recommend this tree for medians and river greenways.  

Ginkgo trees (Ginkgo biloba), also called maidenhair trees for their unique leaf shape, are very interesting.  They are dioecious, meaning that each tree is either male or female.  It is very important to get male trees as females produce foul smelling fruit that is to be avoided.  It has a moderate rate of growth, but reaches up to 50 feet in height and has a 25 foot horizontal spread.  It is drought tolerant, and tolerates almost any soil conditions.  It will grow slowly initially, but does much better if given a consistent supply of water with the Waterboxx PlantCocoon.


A younger Ginkgo tree in a city park along a busy street in Indianapolis.

A more mature Ginkgo tree on a college campus in southern Indiana.

Any discussion of city trees would be incomplete without mention of oak trees.  These trees are renowned for their beauty, strength, shade quality, and wildlife value.

The Northern Red Oak (Quercus rubra) is a beautiful, straight, and fast growing tree well suited for Midwestern cities.  In our experience, it grows as fast as Silver Maple, but without any of Silver Maple's many problems.  It grows in zones 3-8, tolerates many soils, and has a beautiful fall color (hence its name).  It can be purchased here.

Northern Red Oak

Bur Oak (Quercus marcocarpa) is a great, drought resistant oak tree.  This tree will grow farther west than most other oaks (one exception being the Texas Escarpment Oak), but does tend to be slow growing.  It is large, growing 80 feet high with an 80 foot spread.  It grows in zones 3-8, and can be purchased here.  As this tree is slower growing, we strongly recommend planting it bare root with the Waterboxx PlantCocoon, which will provide consistent water and allow faster growth.

A beautiful Bur Oak, with two paths diverging under it.

We have mentioned the Groasis Waterboxx PlantCocoon throughout the above tree recommendations - so what is this?  The Waterboxx (for short) is a ingenious device for growing trees without irrigation or staking.  The Waterboxx consists of a basin for holding water, a special lotus leaf inspired lid to collect dew and rain water, and a capillary wick to slowly trickle water to the roots of the growing tree.  It is placed around a tree right after a tree is planted as a sapling, and provides all water needs for the tree for the first year.  The Waterboxx can then be removed and reused for other trees.  You can see a schematic view with a corner removed below.

A schematic, cut-away view of the Waterboxx PlantCocoon.  Water is collected from dew and rainwater on the tan lid, funneled into the green reservoir, and slowly released to the roots of the growing tree by the white wick.  The tree is induced to grow deeper roots because of the Waterboxx and is more resistant to drought in the future.  


Two trees we would strongly recommend against planting (despite their popularity currently) are Silver Maple (Acer saccharinum) and Bradford Pear (Pyrus callerycana).

The Silver Maple has many problems.  It is fast growing, which is its main (dare we say only) good quality.  However, this growth is accompanied by weak branches and a large number of sticks on the ground after high winds.  It also has very shallow roots which trip people and buckle sidewalks, and are also hit by lawnmowers.  Finally, it is not a strong or long lived tree, and will need to be replaced within a few decades.
The very shallow roots of a Silver Maple

These shallow roots of a Silver Maple have cracked the nearby sidewalk, allowing weeds to grow in the cracks and posing a safety hazard.  
The other tree we strongly recommend against planting is Bradford Pear.  This is also a fast growing, picturesque tree.  However, this tree is fantastically weak, and will split is light winds.  It is a waste of money to plant, and it pains us to see it planted in so many suburban driveways and yards.

This Bradford Pear collapsed in a light rain - no wind to speak of.

If you have any questions or suggestions for other excellent city trees for the Midwest region, please leave a comment below.  If you are interested in buying a Waterboxx, you can find them here in the U.S.