Unusual materials from making raised beds?
This year I would like to heighten the sides of our raised beds. We have 3 central beds made from rail road ties, and I'm ok with those, it's the long bed that encircles the garden that I'm looking to heighten. As it is now, the sides are made of 4x4 pt posts.
I'm wondering if there is a material I'm not thinking of that will do the job? I hate to spend a ton of money on lumber as it's a large garden and most of my budget would go toward wood and not plants. The most economic material I can think of is landscape timbers. They are, I think, 8 feet long and about $4.00.
Any other suggestions?