Rooted in Success

Long-term tree planting success depends primarily on three important factors: good planting techniques, planting at the right time of the year and choosing good plant species and varieties. Selecting the right trees based on existing site conditions will ensure they will establish and thrive with a minimal amount of short- and long-term care or maintenance. It’s almost like doing a puzzle – making sure the pieces fit right.

Urban and suburban site conditions can vary greatly. Often a site will consist of various microclimates as you move around the property. Climatic variations caused by existing structures, buildings, plantings, traffic patterns, parking areas, automobiles, geography and topography. Unfortunately there is no single tree that will tolerate all conditions. Sure, at minimum it’s important to note a site’s exposure to sunlight. Is it sunny or predominantly shade? But more considerations need to be made.

Here’s what Dr. Nina Bassuk at the Urban Horticulture Institute, Cornell University, suggests that you consider when assessing a site for planting. The following is an excerpt from “Recommended Urban Trees,” by Bassuk, taken from the New York State Nursery and Landscape Association’s Certified Nursery Professional Training Manual, chapter 3.

BELOW GROUND
Restricted Rooting Space. Underground obstacles, compaction near curbs and driveways and actual containerization of trees causes restricted rooting space, limiting the amount of water, nutrients and oxygen the roots have access to. Drought-tolerant trees offer some hope; however, reasonable rooting space should be allowed before trees are planted.

Soil Texture. A sandy soil will suffer less from the effects of compaction but may be less able to supply water to trees. Conversely, a heavy clay soil may be too wet due to compaction so that oxygen is unavailable.

Soil pH. Most urban soils have a high pH (nearer to neutral or higher) due to limestone-containing minerals in the street environment. A simple pH test can determine your site’s characteristics. (Author’s note: you can do your own on-site pH test in minutes with a pH test kit.)

Drainage. Poor drainage due to compaction or underground obstacles can easily be judged by placing an open-ended coffee can on top of the soil, pouring water in and observing the time it takes to drain. If the water hasn’t drained in an hour, you may want to put in supplemental drains or choose species that can tolerate intermittent flooding.

Road Salt. In an area of high road salt or sidewalk salt applications, appropriate species can be planted to minimize damage later on.

ABOVE GROUND
Exposure. Excessively windy sites often will place stress on trees with large leaves leading to leaf tatter. Also, trees in these sites may need supplemental watering so they do not dry out as quickly.

Shady sites determined by the sun and shade patterns around buildings may limit choice of trees. Most trees require full sun, but a few may tolerate slightly lower levels.

Building Setback/Overhead Wires. The presence of physical barriers to tree growth above ground such as narrow buildings set back from the street and/or overhead tension wires requires a tree that will not interfere with these structures. Columnar forms of trees with low mature heights (less than 30 feet) can be used in these situations.

Surrounding Building Surfaces. Concrete, asphalt, car tops, mirrored building surfaces, etc. increase the reflected and radiated heat load onto a tree, which can cause it to heat up and lose water from its leaves at a faster rate than normal. Drought-resistant trees should be chosen in these situations.

USDA Temperature Zones. All trees chosen for your planting area should be cold hardy. Urban environments often fluctuate more in temperature due to heat from buildings and sheltering from wind. A good rule is to plant trees that conform to your zone or lower (colder) climates. Trees in containers are more susceptible to cold winter temperatures than trees in the ground.

After assessing your site and choosing your tree, pay attention to good planting techniques including planting during the proper time of the year.

Source: LINLA