If you can not afford to build a fence, there is a cheap option.

This photo was taken by an Asahi Pentax 6 X 7 medium format film camera and Super-Multi-Coated Takumar/6X7 1:4.5/75mm lens using Fuji Reala 100 film, the negative scanned by an Epson Perfection V600 and digitally rendered with Photoshop.