Using free and recycled products to make your garden is one of the best ways to get into SFG. Since it is such an easy and efficient method of gardening, it makes sense to be economic and eco-friendly about building it.  You do have to be very careful about the source of your wood. Railroad ties are soaked with creosote which is toxic. Other woods like pressure treated or painted woods can have toxins in them too. If you get some questionable wood and want to make sure it doesn’t contaminate your soil, line it with some thick plastic sheeting on the side that will touch your garden. Also if you want to paint the wood you use for your garden, only paint the sides that do not touch your garden. You want to know that the food you grow is safe to eat, that is one of the many benefits of growing your own food. Toxins from railroad ties and pressure treated woods can not only poison you and your family but can make the soil barren. Nothing is more important than the safety of you and your family. Make sure the plastic covers all areas that will come in contact with the plants, and you should be well protected.