The International Oleander Society reports that established oleanders do not need to be fertilized to be attractive, but that light fertility may increase growth and flowering. As a general recommendation, apply 2 pounds each of actual nitrogen, phosphorous and potassium to 1,000 square feet of the area landscaped in oleanders, one application each in early fall and early spring. Because of their low maintenance and long flowering, oleanders are very popular along the Gulf Coast and southern Atlantic seaboard and in New Mexico, Arizona and California. Several dwarf varieties are in the trade. Both grow to about 2 feet tall.
Oleanders are generally trouble-free.
The most serious pest may be the oleander caterpillar. Arkay said the caterpillar is rarely found on oleanders planted in highway medians in the midst of auto exhaust and along seashores where they are sprayed with salty mist. Aphids on new growth can be washed away with a garden hose. Scale infestations, though not common, can be persistent and hard to control. Oleander seeds germinate without pretreatment.