Both my cats have used the garden from almost day one they prefere it to cat litter they will use the litter tray at a push but will cry at the back door to go out but my next door neighbours cat uses her tray and has never wanted to use the garden i think it depends on the cat and their preferences personally i would prefere mine to use the tray as i hate going out in the rain and digging up the solids so they have a clean garden

viv xx