I just planted my victoria ceanothus and the leaves are turning brown, WHY.

It needs fertile, permeable soil, adequately moist for the first year and preferably slightly acidic as it might suffer from chlorosis (leaves turn yellow and the plant defoliates when it cannot absorb ferrum from the soil).

Usual cause for browning, specially if they go crispy and fall, is drought. If you've recently planted it, it'll need a gallon of water every 5/6 days (unless we have torrential rain). It's an evergreen, and loses moisture through its leaves all the time and has not yet had time to root into the soil to seek its own water supply.