Landscape and Irrigation is read by decision makers throughout the landscape and irrigation markets — including contractors, landscape architects, professional grounds managers, and irrigation and water mgmt companies and reaches the entire spetrum.
Issue link: http://read.dmtmag.com/i/351389
www.landscapeirrigation.com August 2014 Landscape and Irrigation 19 * Junk fill soil (low fertility and low water-holding capacity) * Presence of construction debris or other buried trash (con- crete, for instance, can leach, causing soil pH in the vicinity to go up) * Runoff from deicing salts (toxic and desiccating to plant roots) * Heat reflected from buildings, paved surfaces, and cars (puts more water stress on plants) * Inadequate soil volume, for trees especially (plants can't get their moisture and nutrient requirements met) Many of these urban stresses are related to soils. Jamie Blackburn was schooled in these as one of Dr. Bassuk's UHI graduates and now works as a consulting arborist. He did his master's research on woody groundcovers for urban conditions and difficult situations like slopes and produced a very useful bul- letin with Dr. Bassuk with suggestions based on his findings (see Resources). Said Blackburn, "Soil assessment and management is some- thing that is routinely neglected in home landscape projects, especially if the home is new construction and the topsoil has been scraped off and the exposed subsoil heavily compacted. Too often, budgets are absolute minimal for things like spreading com- post, tilling, ripping, soil mixing, etc., as well as proper mulching. Homeowners typically are fine with spending money on plants, even at large install sizes, but getting them to realize the necessity of paying for good soil amending is a harder sell." Landscapers could use the resources available on the UHI site to educate homeowners about the critical need to remediate poor soils. Urban horticulturists, especially municipal horticulturists, often have to deal with budget constraints for both materials and labor. They have to think long-range, and ask themselves, "What can we afford not just to install, but to maintain?" said Blackburn. "So often I see situations where a homeowner spends tons of money on a nice new landscape, but does not take into account future maintenance costs, and then the long-term design intent is never realized, and the homeowner then sees the whole project as a waste of money, which is frustrating for everyone involved. Consideration of future maintenance is, or should be, one of the primary factors driving the design of a landscape." Plant material that quickly outgrows its space is a maintenance hassle for busy urban horticulturists. With regard to plant size and Left: This hillside features excessively well drained, sandy soil, so the plants there have to be drought tolerant, much like those used in urban heat islands. Middle: The author planted her south garden with unusual restraint, actually giving the plants adequate space. Considering ultimate size is a key urban horticulture principle. Right: Rugosa roses and purple smokebushes are incredibly tolerant of hot, dry urban conditions and low fertility. Salvias are drought tolerant once established, so they make good perennials for urban use, where plants typically don't get optimum watering. Knowing the true mature sizes and habits of landscape plants in one's climate — and working with those realities — is key in order to avoid the need for annual corrective over-pruning.