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W henever I visit a new client site, I put on my urban horticulturist hat. In this con- text, "urban" means significantly altered by human activity — and what landscapes have not been greatly affected by people? Not just city landscapes, but suburban and exurban landscapes too — especially in terms of soils. Even in the country, where there may be welcome pockets of remnant cow compost, there will also be places on the property where the soil is compacted because of foot or machinery traffic. All home landscapes have conditions that mimic what goes on in cities. For example, my suburban garden along the driveway endures reflected heat from the asphalt, just as any city garden would. Another of my gardens along the main sidewalk gets deicing salts runoff in the winter. The key as landscapers is to identify these challenges (and opportuni- ties) at the outset, and we need a framework for that. The best guide to site assessment is provided by Cornell's Urban Horticulture Institute (UHI) within their free publication called "Recommended Urban Trees" (RUT) (see Resources). It contains a terrific "Site Assessment Checklist" with detailed instructions on how to complete it, and it's applicable to all land- scape plant material, not just trees. The process of site assessment has you consider things like sun and shade exposure, USDA Hardiness Zone, microclimates, underground and overhead utili- ties, available rooting volume, soil texture, pH, and drainage. The checklist in RUT includes visual assessment of existing plants — both cultivated and wild. Noting what's growing well — and what's not — will give you insights into the site conditions. For example, if rhododendrons, azaleas and/or mountain laurels all have lustrous dark green leaves and other signs of vigor, the client's soil is probably acidic to some degree. But if they are consistently showing pale yellow leaves, the soil may be alkaline. This is a very thorough checklist. Will you fill out every box for every situation? No. But using the checklist gets you in the habit of thinking systematically about your site, and then you can engage in some informed plant-site matching. This will bring your client so much more success and gratification than if you use the cookie-cutter design approach, and this will enhance your reputa- tion as a landscape professional who knows what they are doing. Assess for stress Here are some "urban" stresses that we can be on the lookout for on our clients' properties. I learned about these and all facets of urban horticulture from Dr. Nina Bassuk, who directs the Cornell UHI: * Compacted soils (reduces oxygen, water, and nutrient avail- ability to plant roots) * "Boney" native soils (inadequate fertility and perhaps limited room for roots to grow) 18 Landscape and Irrigation August 2014 www.landscapeirrigation.com Industry Insights What Urban Horticulture Has to Teach Us By Michelle Sutton Let's say bearded irises are part of your design template, but does the client's site support bearded irises? All photos by Michelle Sutton