raised garden questions
 

My wife desires a raised garden outside our yard in the greenbelt. We
plan to use the garden for vegetables. We aare debating the use of
landscape timbers, railroad ties, and just regular 2x12 lumber for the
edging. I am concerned about arsenic and coaltar used in the timbers and
railroad ties and want to use 2x12's with 4x4 posts to hold in place and
serve as anchors for fencing material to keep all of the deer out of it.
How high should we make the fence? She is concerned about deer jumping
into the garden, it is approx. 10feet x15 feet. I have proposed a 4-5 ft
tall fence, knowing that the deer could get in there if they desire, but
don't think they will. Does anyone have experience keeping deer out of
such a garden? Your comments on either subject would be appreciated.
Thanks in advance.