I just purchased Oleanders and planted them last week for a privacy fence. The leaves are turning yellow with green spots and falling off. I checked the soil and they have plenty of water. But, I have a sprinkler system that covers the entire lawn. Will this cause yellow leaf drop? There is no way to avoid them getting watered by the sprinkler system. I did fertilize them when I planted them 9 days ago.
Yellowing leaves generally indicate a watering issue.
Though they will need additional water to become established, make sure the soil is draining.
I would avoid fertilizing until you have established growth, and then only if necessary; due to poor soil.
This article will refresh you on the care requirements.