Complex sentence: Although Dark Towers is similar to Husker Red, its red foliage is darker than that of the Husker Red cultivar and has more height and it stays red for a longer time in the summer.
Split into simpler sentences: Although Dark Towers is similar to Husker Red, its red foliage is darker than that of the Husker Red cultivar and has more height. It also stays red for a longer time in the summer.