这个.没有前后文咱也不是很清楚,大概是这样.
the outskirt of the garden 【in which Tess found herself 】had been left uncultivated for some years,and was now damp and rank with juicy grass,...
【in which Tess found herself 】是修饰the outskirt of the garden 的定语从句,后面的had been left uncultivated for some years,是主句的谓语.所以应该是这个意思:the outskirt of the garden been left uncultivated for some years,and was now damp and rank with juicy grass,...而不是Tess found herself had been left uncultivated for years...
主句的谓语动词had been...,and was...,定语从句的谓语是found.