The stately tulip tree (Liriodendron tulipifera) has shaded American yards since Colonial times. Soaring up to 150 feet, with most specimens from 60 to 90 feet tall, tulip trees have columnar trunks that seldom have low branches, according to the Missouri Botanical Garden. Named for their tulip-shaped spring flowers and foliage, the trees are desirable ornamentals and important commercial lumber sources. Growing them in locations where winter means high winds and road salt spray, however, has its challenges.
Tulip Tree History
The state tree of Indiana, Kentucky and Tennesse, the tulip tree is the tallest native American broad-leaf tree, and the second largest, behind the sycamore, in terms of volume. Records indicate that some trees grew to 200 feet with 12-foot diameters, say Forest Preserve District of Cook County President Richard B. Ogilvie and Superintendent of Conservation Roland F. Eisenbeis. The largest measured tulip tree as of 2010 is in Chesapeake County, Virginia. It stands 115 feet high, with a nearly 30-foot circumference and 83-foot spread.
Salt Spray Tolerance
Tulip trees are vulnerable to damage from salt spray exposure, says associate professor Dr. Wayne K. Clatterbuck, Ph.D, of the University of Tennessee Agricultural Extension Service.
Symptoms of Exposure
Tulip trees exhibit symptoms of exposure throughout the year. Their flower buds open slowly or not at all. Their leaves may be fewer and smaller, with reduced green pigmentation that fades earlier in autumn. Foliage may drop sooner than that of unaffected trees. Foliage density varies from year to year depending on the amount of salt spray exposure, says Clatterbuck. Symptoms are more noticeable on the side of the trees closest to the road.
As tulip trees accumulate salt, their absorption of water and soil nutrients decreases. Soil high in sodium breaks down, making water drain more slowly and compromising soil oxygen levels, notes Dr. Clatterbuck. Salt attracts water, so water tends to stay in soil instead of entering the tree's system. When a tulip tree does absorb salt from the soil, its leaf cells dehydrate.
The tall, single trunks and high branches of mature tulip trees make them susceptible to storm damage from wind, ice or lighting, according to the Ohio State University Plant Facts Website.
Topping trees periodically will reduce wind damage. To protect the trees from salt spray, plant them at least 60 feet from the roadside. Remove snow or slush piles where salt might accumulate. Thoroughly irrigate around trees exposed to spray each spring. Doing so leaches excess sodium from the soil. Reduce sodium levels even more by amending sodium-rich soils with calcium sulfate (gypsum) to improve drainage and oxygen levels. Water, feed, mulch and prune all trees with symptoms of salt exposure.