Oleanders can reach a height of 20 ft. or more. Its leaves are willow-like, linear-lanceolate, and glossy green in color. Oleander is not at all fussy about soil. Oleanders are susceptible to a fatal disease called, oleander leaf scorch. Deadheading will help freshen the plant and encourage it to fill out but is not absolutely necessary. It is the only species currently classified in the genus Nerium. They are covered in waxy coating to reduce water loss (typical of oleanders). I have consulted with several cases affecting large, mature oleanders in Arcadia, Biltmore, and Moon Valley areas in Phoenix. They can be made into a single trunk tree or a multi-trunked tree. Planting Oleander Shrubs . Oleander plants will repeat bloom from spring through fall. From the Mediterranean, this floriferous, fast-growing beauty is a staple in landscapes across the Western United States. Can I turn them into trees by cutting all the branches to the ground except for the largest, fattest branch in the middle? Flowers bloom from summer to fall. Oleander, Nerium oleander, is a super drought tolerant evergreen hedge or tree that can add vibrant color as well as privacy to your landscape. Oleanders can make very nice small trees but the suckers at the base will be a problem for a few years. Keeping them trimmed to a nice size is going to more than likely force out more blooms, which is without a doubt the best value of the plant (in my opinion!). There are dwarf versions of oleanders that do not mention these massive heights for even less maintenance required. Nerium oleander / ˈ n ɪər i ə m ˈ oʊ l iː æ n d ər /, most commonly known as nerium or oleander, is a shrub or small tree in the dogbane family Apocynaceae, cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. Period of Bloom . Its stem is green turning silver/gray as it ages. They can be kept smaller by pruning, but you will have to keep at it. It's a small to medium sized plant that makes an excellent 'Living Fence'. Q: I have two 7-foot-tall oleander bushes about 8 feet apart. This disease has come from California into Arizona where it is popping up in neighborhoods in Phoenix and also Lake Havasu. Growing to a height of up to 20 feet, it can be a bit gigantic in scale. Cascabela thevetia is an evergreen tropical shrub or small tree. Most oleander cultivars reach a height of 8 to 12 feet and spread to cover an area of about 10 feet when fully grown.