The tulip poplar (Liriodendron tulipifera), also known as yellow poplar, is a fast-growing tree that has a life expectancy of 300 years if growing in optimal conditions. In urban/suburban settings, most specimens will more likely live between 100 to 200 years. Tulip poplars are not poplars but members of the magnolia family. They are tall, fast-growing shade trees that easily grow to 70 to 90 feet and can grow to more than 100 feet. They are considered relatively hardy trees with few insect and disease problems. With proper planting and maintenance, you can help your tulip poplar live longer.
Tulip poplars have attractive green leaves that are tulip-shaped. The flowers also resemble tulips--they are yellow with touches of green on the six petals and bright orange in the interior. Often the flowers are too high up in the tree to see and appreciate. The trees do not flower until they are 15- to 20-years old. By then, the tree may be as high as 40 feet. Young trees have smooth grey bark which later becomes very furrowed as the trees mature. A cone-like structure produces the seeds, which are winged samaras, in August in the north and as late as October in the south. Tulip poplar is a prolific seed producer but only a small percentage of the seeds will be viable.
Planting and Site Selection
Tulip poplars grow best in moderately moist, well drained and loose textured soils that are slightly acidic (pH 6.0 to 6.5). They are native to North America and recommended for U.S. Department of Agriculture plant hardiness zones 4 to 9. They grow faster and higher in more southern locations. Tulip poplars can be purchased from nurseries and transplanted balled and burlapped in the spring. They may grow 15 to 20 feet in a six- to eight-year period. Choose an open location with full sun. They are not recommended for small residential properties or streets.
Because tulip trees are fast-growing they are moderately weak wooded making them susceptible to wind or ice storms. Broken tree limbs make trees more susceptible to wood rots. Prune off dead or broken limbs to prevent wood rot fungi from entering the trunk of the tree. When pruning limbs, always prune back to the branch collar. The branch collar is a slightly raised area between the trunk of the tree and the limb. Do not cut into the trunk of the tree to prevent insects and diseases from entering. A nice, even cut at the angle of the branch collar encourages the tree to callus over (heal) naturally. Tulip poplars naturally prune their lower limbs as they grow. The first limbs on a tulip poplar may be quite high up in the tree. For safety reasons, it is better to hire a professional arborist to climb the tree and carry the heavy equipment needed to trim the higher branches. Branch trimming is best done in the dormant season in winter or early spring.
Aphids and scale insects are sometimes pests on tulip poplars. They secrete honeydew on which a sooty mold fungus grows. The mold makes the trees less attractive and blackish moldy leaves drop to the ground prematurely creating a mess. The insects rarely cause mortality in large trees but do cause aesthetic problems. If you decide to treat your tree, hire a professional applicator to make soil or trunk injections of a systemic insecticide such as imidacloprid. You must plan in advance, however, because it can take a few weeks for the product to get from the soil or trunk to the growing points of trees. Foliar sprays work faster but it is often difficult and impractical to spray large trees, plus there is a risk of harming beneficial insects that are natural enemies of the aphids and scale. Watering the trees during droughts will help them resist the insect pests.
Your Planting Articles
- Manual of Woody Landscape Plants, Michael A. Dirr
- National Forest Service:
- USDA NRCS Plant Fact Sheet: Tulip Poplar
- University of Connecticut Plant Database: Liriodendron tulipifera
- Purdue Plant & Pest Diagnostic Laboratory: Sap-sucking Bugs Make of Mess of Indiana's State Tree
- University of Califormia IPM Online: Aphids
- New Mexico State University: Tree Pruning Techniques