I recently planted a leucospermum. Now some of the leaves are turning yellow on the bottom third of the bush. What would cause this? I have it in a 1/2 wines cask outdoors(bottom knocked out). I've had it on a drip watering system that waters it every 2nd day for 30 minutes. I've now cut the watering back to every 3rd day for 15 minutes. Is this still too much?
Drainage is very important, so you will need to check the soil instead of watering on a schedule.
Yellowing leaves can indicate watering issues, pest and disease.
This article will refresh you on the care requirements.
The plants are about 2 1/2 years old and doing very well. We have two of them on a hillside and they need to be contained.
Pruning consist of deadheading, mainly. In order to control the spread, you will need to cut and dig out sections. In order to retain this, permanently, you can sink a garden border deep into the ground in the area that you want the plant to remain.
Here are some articles that will offer more information:
Can my leucospermum be pruned right back? Appears to be dying after severe long term rain. How can I revive it?
Trimming will be, only, part of correction. You will need a fungicide to correct the issue, though.