The tulip tree is the state tree of Indiana, and is also called yellow poplar, tulip wood and canoewood. According to the University of Virginia, there are several cultivars of tulip tree, but none is significantly different from another. The tulip tree is a monster of a shade tree that grows straight to a height of 100 feet with a trunk diameter of 4 feet to 6 feet or more in many sections of Indiana. Its tulip-shaped flowers in spring and bright-yellow fall color give it three-season interest in the Indiana landscape.
Select a site for planting a tulip tree that is well away from sidewalks, driveways and streets. Its surface roots can heave pavement, and falling blossoms rot quickly and make a mess on cars and shoe soles. Find out where underground utility lines are located, and plant tulip trees 50 feet or more away from them. Be sure to look overhead, and avoid planting under power or telephone lines. Tulip trees like full sun, so plant them in open spaces. In Indiana, no special soil amendments are necessary — plenty of water and sunlight will have them growing 3 feet to 4 feet per year.
Water newly planted tulip trees every other day for the first month after planting to help the roots get established and to reduce transplant shock. After that, Indiana’s rainy weather should provide adequate moisture. In times of drought or intense heat, water to a depth of 4 inches once a week over the root zone of the tree. Determine the root zone by looking for the drip line of the widest branches. Fertilizing is not necessary, and can even hurt the tree, causing a burst of vegetative growth that dies in winter, especially if applied late in the growing season.
Spread a 3-foot ring of mulch at a depth of 2 inches to 4 inches, beginning 6 inches from the trunk of tulip trees. Mulch will hold moisture over the root zone and will regulate soil temperature by insulating it from heat and cold. Don’t allow mulch to pile up against the trunk, because it will rot the bark in as little as one year, girdling and killing the tree. Rake out and replace mulch annually to renew nutrients, keep weeds down and prevent the buildup of fungus and bacteria in the soil underneath.
Prune tulip trees to encourage height by trimming off the lowest branches on the trunk once a year. Tulip trees will naturally grow straight as an arrow, so very little pruning for shape is necessary. Always angle shear blades at 45 degrees, cutting down and away from the trunk. Leave a half-inch stub that drains moisture instead of collecting it and causing rot.