I always get asked “How far from a fence should I plant my Thuja Green Giants”. The answer is simply “8 feet” from the fence. If you plant closer than this you risk having the plants grow into the fence.Just another quick tip for planting your Thuja Green Giant Trees! always get asked “How far from a fence should I plant my Thuja Green Giants”. The answer is simply “8 feet” from the fence. If you plant closer than this you risk having the plants grow into the fence.