A good understanding of microclimates will allow lawn care professionals to improve turf quality
By Mike Jiggens
Not all lawns are alike. It’s also true that there can be vast differences in certain areas within the same lawn. Roof overhangs, trees, reflective surfaces, confined spaces and the soil itself contribute to different microclimates within a lawn. To successfully manage a home lawn, lawn care professionals must be aware of how variances in air, light, humidity, water and soil can produce different microclimates, which affect turf quality.
Mike Van Beek, an instructor with the University of Guelph’s turfgrass management program, spoke at the Ontario Turfgrass Symposium about the step-by-step process in identifying and assessing specific microclimates and growing conditions on lawns that are managed by lawn care professionals. The symposium was presented during the winter in a virtual format due to the ongoing COVID-19 pandemic.
Even the smallest of yards can have a variance that produces a microclimate, he said. By definition, a microclimate is the climate of a small or restricted area, especially when it differs from the climate of the surrounding area.
Exposures associated with buildings, sheds, screens, fences and other structures can contribute to a microclimate.
“Each one of these particular exposures can have its own unique microclimate associated with it,” Van Beek said.
A southern exposure may get more sun versus that of a northern exposure, while an eastern exposure may get less wind than a western exposure. Each situation may have its own microclimate. The reflection of sunlight off of a surface and onto a lawn could cause a particular area to heat up more or warm up earlier in the spring, thereby creating a microclimate.
Little nooks and crannies on a property may be protected from the wind, yet are exposed to the sun for longer periods, creating microclimates. Some homes have roof overhangs that reach out further than those of others, impacting the amount of moisture on the lawn directly beneath.
Trees and shrubs are among the most common contributors to microclimates, Van Beek said.
“As they get larger, they can impact the turf underneath by how much shade they give, or if whether they get full sun or filtered sun down through the foliage. That can have an impact on the microclimate underneath the canopy of a tree of a shrub.”
Trees can also block wind, creating humidity concerns that could lead to peripheral pest problems.
Confined spaces and shade
Confined spaces tend to produce cool, moist and humid conditions. Trees growing in close proximity with each other can create microclimates that present a challenging growing environment for turfgrasses.
A shade canopy may not only reduce temperatures, but will block wind that could cause temperatures to increase. Trees and shrubs also compete against turfgrass for water and nutrients at their base.
The soil itself can create both microclimate and growing challenges, Van Beek said.
“Inconsistent textures and depth of topsoil can create little microclimates within the turf growing area.”
If soil inconsistencies are prevalent throughout a lawn, the resulting turf growth will be just as inconsistent, he said. This is especially common in new subdivisions, where topsoil is removed to allow construction to take place and then is pushed back in place, but often at varying depths.
Traffic patterns on lawns can lead to compaction and the creation of microclimates, affecting root growth and altering the quality of turf.
A lawn’s topography can have a bearing on microclimate creation. The ability to hold water may be compromised on slopes while hollowed depressions may hold rain for longer periods of time. Low spots can produce thin turf due to prolonged wetness after a rain event. The texture of the soil beneath may contribute toward reduced drainage. Heavy traffic in the area may also be causing compaction.
“These are creating little microclimates that could pose a problem for the turf.”
Create a site analysis
Van Beek suggested lawn care professionals conduct a site analysis upon arriving at a customer’s property for the first time. They should perform a “big picture” analysis of the site and record a written inventory for future reference. Professionals should make note of all possible contributors to microclimate creation, such as trees and topography. Taking photographs is also helpful, he said.
“Walk the property and evaluate the strengths and weaknesses of existing turf, available light and soil conditions. This information goes into the site analysis. With that, you come up with the remedies and solutions for the concerned areas on the property, and that will help you develop the program you want to implement for that site.”
Van Beek said lawn care professionals need to be able to identify the more common grasses found in a standard lawn, including Kentucky bluegrass, perennial ryegrass, fine fescues, tall fescue, annual bluegrass and perhaps some native bentgrasses. Once the grass types have been noted, the approximate percentage of each and their location on the lawn should be documented.
Changes in the percentages of different grasses could be a reflection of the soil type. Different microclimates may have an impact on the grass types growing in these spaces, he said.
Once the various grass species have been identified, the species most desirable for the site should be promoted, Van Beek said. A composite of different grass types might exist, but they should be ones that perform well under circumstances associated with their particular microclimates.
Broadleaf and grassy weeds, including dandelions, plantain and clover, also need to be identified as well as the time of the season they are prevalent. The percentage of the lawn they occupy should be assessed, he said, and the homeowner should be consulted to determine an acceptable threshold.
“Is the client tolerant of a small percentage of broadleaf weeds? Do you slowly try to outcompete them with a good offence of healthy lawn grass, or does the client want them eliminated immediately? Are the broadleaf weeds localized or are they located throughout the entire lawn? If they are localized and there are only small pockets, is there a correlation to microclimates that might be causing these concerns?”
Assess turf density
Van Beek said the density of the turf stand requires analysis. Thin stands could be the result of microclimate variations. He suggested soil conditions need evaluation. By digging into the soil, the depth of topsoil will be determined. If a healthy base isn’t present, it could be a contributor to poor turf quality. The soil’s texture can help with a diagnosis. Clay can contribute to a compacted soil while sand could challenge the ability to keep the soil wet.
“Being able to look at the soil and evaluate what’s under the turf will go a long way to help you diagnose whether a microclimate of soil concerns is helping your turf or contributing to some of the concerns you see.”
Taking soil samples and having them analyzed by a lab will determine if there are nutrient deficiencies. Such information will help lawn care professionals customize their fertility programs.
Surface drainage issues may be addressed by building up low spots. Shade issues may require pruning the lower limbs of trees or thinning them out to promote more sunlight.
Van Beek said even the best-quality turf and soil will be impacted by drought that could last for several weeks.
“If you can see greenery at the base of the plant, there’s a good chance the plant is still alive and dormant.”
If the turf is “crunchy” underfoot, however, and it’s evident that it’s crumbling away at its base, chances are it’s dead, Van Beek said.