b'Cooling the Concrete JungleNew greenspace plant varieties are key to keeping urban spaces livable.Melissa ShipmanCITIES HAVE ALWAYSheld heat more than non-urban spaces, but theyre heating up especially fast in our new changing climate reality.Urban heat islands (UHI) are created by large expanses of concrete, pavement, buildings and other surfaces that absorb and retain more heat than natural land cover. According to the World Health Organization, inland cities can experience temper-atures three to five degrees Celsius (5.49 degrees Fahrenheit)Improved cultivars and genetics in all species will allow turf higher than surrounding plant-covered areas. The United Statesto tolerate stresses and require less inputs, says Leah A. Brilman, Environmental Protection Agency found a much bigger differ- director of turf products and technical services for DLF.ence, stating daytime surface temperatures can differ in devel- While plantings are designed to mitigate rising temperatures, oped versus natural areas by as much as 27F. With climatethey first have to themselves survive the high heat.change exacerbating an already significant problem of exces- A lot of cool season grasses stop growing when tempera-sive heat in urban centers, cities must work to break up thesetures reach higher than 25 or 30C [77-86F]. It is our goal to concrete jungles with green spaces. The seed industry has anhave grasses that keep growing into 35C, van den Boom says.important role to play. Warm seasons grasses can withstand higher temperatures I think were going to see a lot more science involvingbut go into winter rest when temperatures drop below 60F. thermal comfort, and how we can utilize turfgrass and otherDue to climate change, we see that we are using warm-sea-urban vegetation to mitigate some of these heat events by re- son grasses in more and more places, van den Boom says.greening cities, says Michael Barnes, researcher and lecturer atSunlight is another main concern. the University of Minnesota. The simple answer is always plantFine fescues perform well for low maintenance either mown more trees but thats not entirely the solution. Its an and, notinfrequently or unmown, sun or shade, Brilman says, while an or. The goal is to plant more climate-ready trees and turf andseeded Bermuda grasses can do an excellent job for green other vegetation. spaces in the transition zone and south, as long as they receive Adding green space to cities adds to quality of life in manyadequate sunlight. ways: providing improved water filtration and drainage, increas- Low water use and high heat tolerance make them excellent ing oxygen production, reducing carbon dioxide and improvingfor small areas exposed to heat and for parks and sports fields, air quality by trapping dust and other airborne particles.she says.The fastest, most effective and most affordable way to do this is to sow more grass, says Jan van den Boom, turf sales leadLow Maintenance Mattersfor Barenbrug Holland. Both homeowners and city planners focus on selecting seeds that will provide low maintenance growth.Breeding for Extremes We really need to focus on identifying and develop-Successful urban plantings require careful consideration anding drought tolerant grasses, says Eric Watkins, professor in expert knowledge on selecting seeds that will thrive in condi- the Department of Horticultural Science at the University of tions that are often extremely unfavorable. Minnesota.74/ SEEDWORLD.COMDECEMBER 2023'