Research and Development

Research & Development

One might think nature is hard enough on plants - between freeze/thaw temperature fluctuations, wind, rain, hail, ice, tornadoes, humidity and sun - a plant is constantly acclimating to the weather.
But when we transplant trees into the city landscape we are creating the Ultimate Challenge – Extreme Landscaping. There is no harsher environment than the urban environment. And only the toughest conditioned plants will survive and thrive.

The Urban Landscaping is made up of blistering hot streets, schoolyards, heavily trafficked parks, riverbanks, cemeteries, vacant lots, parking lots, utility rights of way, and adjacent woodlands. It includes not just plants, but animals, microorganisms, people, vehicles, streets, sidewalks, buildings, utilities and pollution that are all competing for the same space, air, water, and earth. Each city street has its own extreme microenvironment.
Unlike many managed landscapes, it is often difficult to give the proper follow-up care to a city or roadside planting. The goal in selecting the best plants for urban sites is to find tough but attractive plants that will survive. Learning the hard way and planting trees twice is not fun or profitable.

Why Landscape the City
in the First Place?
Yes, urban landscapes provide beauty, but they also release oxygen and absorb CO2 and other air pollutants. The more urban plants, the less storm runoff occurs, which increases soil moisture and can help recharge aquifers.

Did You Know...

Downtown Chicago trees live About 7 years
Suburban trees live about 30 years
Natural trees can live 100's of years

Plants provide temperature control by changing sunlight to energy instead of heat, cooling the air by transpiration, and providing shade and insulation for buildings. This means less energy use, saving money and natural resources.
Plants have also been linked to a relaxation response in people, helping to create safer and healthier communities. Plants are also a good investment, increasing property value in homes, and increasing pedestrian traffic for urban retail sites.

The urban landscape design must put site conditions first and personal preference second.
The problem in selecting plants for urban sites is finding the right mix of toughness and beauty. Urban plants must tolerate extremes of climate, soils, injury, and space restrictions, but also provide ornamental appeal. Despite the long list of difficulties in urban sites, there is a nice list of plants to choose from that will do well. The key is selecting the right plant for the right site. This means putting aesthetics and personal preference second to site conditions. This does not mean, though, that you cannot get the texture, form, and color to create visual appeal. There are a number of urban tolerant plants that are not only adaptable to a wide range of site conditions, but also provide function and visual appeal.

CLIMATE TOLERANCE
Problem/Difficulties	Solutions
Urban areas are made up of different microclimates created by reflected heat, frost pockets, wind or large bodies of water	Select pants hardy to the region, that are tough and adaptable and tolerant of heat and cold. Also purchasing locally grown plants that have pre-adapted to the climate increases the chance of survival.
Sunlight patterns around buildings	Select adaptable plants that tolerate full sun to partial shade, also place shade tolerant plants in sites that are mostly shaded.
Water Natural or Irrigation	Select adaptable plants, or select certain plants if the site is consistently dry or wet. Also know your nursery supplier's irrigation practices, the more supplemental water they provide the plant, the less likely it is to have adapted to dry conditions and will not have the strength to survive dry urban sites.

SOIL TOLERANCE
Problem/Difficulties	Solutions
pH in many urban sites is on the alkaline side, because soils near the pavement, masonry & foundations contain limestone	Select alkaline tolerant plants.
Soil near pavement contains sodium leached from the concrete	Select plants that tolerate soil salt.
Compaction and Drainage If soils are sandy there is less compation but also less water retention; if soils are clayey there can be compaction, and too much water	Select adaptable plants or select specific plants for the soil type. For compacted soils, select trees that naturally occur in areas of low soil oxygen such as swamps and floodplains.
Soil layer disturbed, recent construction, debris or weeds	Select plants that tolerate harsh environments. Massing or grouping can increase visual impact and increase health and survival of the plants.
Erosion	Plant groundcover type plants to not only improve the appearance of the site, but also help in erosion control.

CONTAMINATION TOLERANCE
Problem/Difficulties	Solutions
Salt spray from nearby roadways	Plant salt tolerant plants, especially near roadways or sidewalks.
Soil contamination, air pollution	Select pollution tolerant plants.

INJURY TOLERANCE
Problem/Difficulties	Solutions
Plant injury from vandalism, dogs, cars, lawnmowers, or bikes	Decrease mower damage by mulching around trees. The less grass around a trunk, the less mowing, and the less chance for mower or trimmer damage. This also means less weeds and less weedkillers.
Monocultures create pest/disease problems	Diveristy is very important in urban sites, where certain plants tend to be overused, creating devastating pest or disease outbreaks. Ideally, there should be no more than 5% of any one species and not more than 10% of one Genus.

SITE RESTRICTIONS
Problem/Difficulties	Solutions
Limited space above ground - including overhead wires, buildings and structures, heat vents, signs and emergency access lanes	Select plants based on their mature size and shape. Utilities spend millions of dollars every year pruning or removing trees that are too close to power lines. Not only are trees too close to power lines hazardous, but severe pruning creates unnatural and unsightly looking trees. To prevent this, use only low growing trees that at mature height do not come close to the lines.
Property Lines	Again select plants based on their mature size and shape. Select low maintenance plants to keep friendly neighbors.
Limited space below ground because of utilities or structures	Root volume has a lot to do with the environment a plant has adapted in. Trees that have adapted to dry areas naturally have a larger root volume. In a site with limited rooting space, use trees with smaller root volumes and be sure to provide adequate water

Growing plants that will thrive in an urban environment requires rigorous training and conditioning. Still, only the best will survive. How a tree is conditioned determines whether it has the kind of root system and cell structure that will give it an advantage. Planting depth, root pruning, heavy clay loam soils, proper digging and handling all go into a tree that has a chance. Northern winters and summers in open fields will give the young trees the proper upbringing to make them competitors when the big transplant day comes. To maximize tree health, which does not always mean maximizing growth, the trees are monitored for diseases and pests and treated in the least toxic manner. Plants that are too pampered in their growing site will require pampering in the landscape. It is a lot like moving a houseplant from a controlled inside environment to an out-of-control outside environment.

McHenry County Nursery and Glacier Oaks Nursery have drip irrigation to prevent plants from going into a shut-down mode during droughty times, but we let nature do most of the routine watering, even when things get a little dry. We check our soil pH and nutrient content annually in the field and far more often in containers to make sure we are providing adequate nutrient availability to plants, and we fertilize only when we drop below an established threshold. We monitor pests and weeds and tolerate some rather than pristinely cultivated growing areas so that we can maintain nature’s balance of letting the good bugs rule. It has been shown in recent studies that a tree provided with maximum levels of nutrients can actually be a calling card to pests as much as a tree with below minimum levels of nutrient availability.

We are constantly looking for ways to improve and refine our container growing to ensure our plants make a smooth transition from pot to lot. “Soil” in urban planting areas is stretching the limit on the definition of the word! For this reason it is better for growers to balance inputs --to maintain a natural vigor of the plants, not ultra-enhanced growth from fertilizer and growth regulators. We like to think of our fields as a savanna laboratory- where some of nature’s most difficult growing conditions exist.

Provenance of plants in urban situations is another growing concern. Stick with plants that originate from the relative climate in which they will be landscaped. By planting trees from warmer zones, it multiplies the difficulty they will have in acclimating to the new site. Losses can be minimized if plants have the advantage of greater capacity to tolerate conditions similar to the weather environment from which they originated.