Tulip trees require little extra work when it comes to fertilizing; one application in autumn is often enough, but you can boost growth by another spring application if you wish. Picking out the fertilizer is the most time-consuming part of the whole process. Once you have the fertilizer, this is a quick job with a big reward: a beautiful, healthy, bloom-covered tulip tree.
Decide what kind of fertilizer you wish to use: A complete granular fertilizer provides a balance of the three main essential nutrients plants need (nitrogen, phosphorus and potassium) but is generally not organic and can cause chemical runoff into the surrounding area. An organic fertilizer, such as bonemeal, bloodmeal or fish emulsion, generally has a concentrated amount of one of the main essential nutrients and a lesser amount of the other two, but they also can improve soil structure. A slow-release fertilizer spike or Osmocote fertilizer releases nutrients slowly into the soil in the same balance as a complete granular but over a period of months rather than weeks.
Wait until flowering has ceased in autumn, then rake back any mulch around the base of the tulip tree so that the fertilizer will reach the soil.
Apply the fertilizer to the soil around the base of the tulip tree. Follow the package directions to determine the amount to apply.
Water the tree thoroughly.
Rake the mulch back around the base of the tree.
Wait until spring. If growth and flowering are slow, apply another dose of fertilizer to promote leaf growth and blooming.