I became the joke of the neighborhood when I bought one and planted it in my landscape. But jokes aside, it is hard to beat. Some horticulturists believe the ornamental pear is over planted, and I started to buy into that idea. But this tree is one of the most dependable for color from year to year. When we look at fall color scientifically, words like carotenoids, pigments and chlorophyll enter into the discussion, as does auxin, gibberellins, other growth hormones and enzymes.
Good conditions boil down to cool night temperatures and warm, sunny days make great fall colors.
Climatic conditions have the most effect on the production of anthocyanin pigments which intensify the red and scarlet colors. Conditions that most favor these colors are sunny days and nighttime temperatures between 45 degrees and freezing. Even though the chlorophyll content of the leaf declines in the fall, it is still important that photosynthesis take place. If an abundance of cloudy weather prevents photosynthesis from occurring, leaf color will be mediocre even if temperatures are ideal. This also can weaken the leaf, making it easy for a northern wind to blow it off the tree.