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www.urban-forestry.com 33 I recommend conifers for parks but not as street trees because you need to be able to have visual clearance from your street trees. Also, conifers are more prone to insects and diseases than deciduous trees. If you're deciduous, you get rid of your leaves every year, but if you're evergreen, you have to live with some portion of your leaves/needles for two to five years—and that's more time for insects and pathogens to get established and damage the tree. Also, a wider variety of insects and diseases affect conifers than do deciduous trees. Lastly, conifers tend to need cooler temperatures, more mois- ture, and better soil than deciduous trees. That said, there are a number of tough conifers for urban use. White fir (Abies concolor) can take hotter temps and the full range of soil pH. It's not fast growing but it's beautiful and a good substitute for Colorado blue spruce. When crushed, white fir needles smell like tangerines. Another fir that isn't planted as much as it should be is Nordmann fir (A. nordma - nianna), which tolerates high pH soils and grows fast. Korean fir (A. koreana) needs acid soil but if you have that, you'll be treated to early, upright purple cones that knock your socks off. It needs a pH below 7.0 or will get chlorotic. Spruces are generally more forgiving than firs. Serbian spruce (Picea omorika) is a wonderful, easy-to-grow tree. Norway spruce (P. abies) is easy to grow (perhaps the easi- est of all spruces) but gets huge and loses its bottom limbs as it matures. Oriental spruce (P. orientalis) is a beauty that should be grown more, with its dark green, tiny little leaves. We're losing a lot of pines, like Austrian pines (Pinus nigra) to diplodia tip blight, which is a real shame; the Austrian pines were so tough and salt tolerant. A beautiful alternative is limber pine (P. flexilis), which grows fast, matures large, is pH-flexible, and is hardy to Zone 4b. Perhaps the most commonly available cultivar is 'Vanderwolf's Pyramid', which is a little bit narrower. Another pine I really like is Japanese white pine (P. parviflora), a five-needled pine with great architectural beauty (has more negative space than the aver- age conifer). One that I like that I'm watching to see how it performs is Himalayan pine (P. wallichiana), a five-needled, fine-textured pine where the needles droop in a showy way and sway in the breeze. Hardiness might be an issue—I think of it has hardy to Zone 6 or 5b, but last spring in Ithaca we had a really cold April after a warm March, and that fluctua- tion seemed to take its toll on some of the Himalayan pines here. But then, seasonal anomaly can affect any trees, not just evergreens. I'm not a big arborvitae (Thuja) fan but 'Green Giant' is a fantastic hybrid of Thuja plicata and T. standishii that grows exceptionally fast and is readily available in the trade. I planted a few out in the deer corridor of my property and they did get eaten but not to the extent that eastern arborvitae (T. occidentalis) would. Where most arborvitaes tolerate or embrace semi-shade, the Spring Grove arborvitae (Thuja pli- cata) grows great in the dense shade and is gorgeous there on my property. —Nina Bassuk, Director of the Urban Horticulture Institute, Cornell University Korean fir (Abies koreana) works well in urban situations so long as soil pH is below 7.0. Photo Courtesy Cornell Woody Plants Database Despite the total failure of the first plantings, the second plantings are all growing well and a few have exploded with new growth. The only difference was the planting height and the super porous mix brought up to the root ball. These second plantings went through the drought of 2012 with little additional watering. Given time, the huge mounds tend to mellow out and settle lower and the lower branches tend to help hide the fact that the balls are sticking 18-24 inches (46-61 cm) up in the air. I have since used this method with good success to plant other conifer species, such as Juniperus scopulorum, that tend to struggle with midwestern soils. I believe that midwestern land- scapers and arborists can plant a much wider array of conifers than was once commonly thought. A partial list of species planted with this method: —Ryan Russell, Horticulturist, City of Columbia, Missouri Abies homolepis Abies koreana Pinus armandii Pinus monticola Pinus ayacahuite Pinus flexilis Pinus strobiformis Pseudotsuga menziesii