This may not be everyone's cup of tea, nor do I intend it to be the way to plant a traditional, functional garden of vegetables, herbs, flowers, perennials and annuals. There are thousands of books and other ways to learn how to plant gardens without rust, and I'm not referring to the botanical disease caused by parasitic fungi.
From personal experience, I can shed some light on how to have your own rust garden. First, it helps if you walk now and then by roadsides or in the country, along railroad tracks or even in parking lots. Equally important is you must notice and be passionate about what other people see as decaying metal junk. The rest is relatively easy. If you plan ahead and wear a backpack, you're smarter than I was for decades.
I will give several examples of where to find suitable rust. One is at the side of any road you walk; there will be interesting car parts which are usually broken, and either rusting already or just beginning. They are often twisted beyond recognition, which adds to the appeal (for me). Metal road signs are also at the mercy of the elements and bad drivers, or knocked over by joy-riders, just waiting for salvation in your rust garden.
The best rust I find is when we go camping or in the woods behind my mother's house. People once buried their trash or dumped it in the woods. There are now laws against this, but it's historical fact. There are still those among us who do not recycle, who litter, who may drive their trash to a town dump, but in many places, there exists a method of trash or garbage collection, the cost of which is either hidden in your taxes or you are billed by independent contractors. I don't know all the details; it's the evolution of civilization.
Back to what I do know: last year I found a heavy chamber pot, half-buried near a stream in the woods, so rusted that it would no longer serve the original purpose. A holy grail, in my eyes. Oddly, both handles withstood the damages of time. This is science too, the slow decay of matter, oxidation and corrosion of metals. Parts of old tools, rusted fences, half of a rake, large gears that once served some simple utilitarian purpose in a farming village wiped out by disease. History rusting among abandoned apple orchards, awaiting resurrection.
The rust found at the ocean is from shipwrecks and pirates, disaster and death. The salt of the ocean, the tides, the moon, being in the right place at the right time may yield part of a grid-like step, rusted to shreds but held together by barnacles, coal tar and starfish. This is ecology and chemistry at its best. You hold it wondering what story this could tell, as bits of it fall, fragile, exposed to sea air and human touch.
In some ways it's like collecting anything; you develop your own criteria. Just a small bit of advice is warranted here, don't be greedy or you will end up with a junkyard and no one will understand you and the town will probably condemn your property, bring in a bulldozer and you'll end up homeless and rustless. I have seen this happen, more than once, and it's truly heartwrenching.
As in all things, there are variations. You can ride a bike instead of walking. You can have a traditional garden as well as a rust garden, or combine the two. You can do neither, although gardening can be very therapeutic. The hardest choice for me is placement, as in along the driveway or in the back yard or right outside the front door, where in January snowdrops will bloom, then crocus, then lilies of the valley. You need to feel confident in your love of rust and ruin, carefully placing each piece, as if they are communicating something timeless, even to the casual dog walker who glances at your garden in Spanish.
This type of gardening costs nothing but time. Side benefits include: no back-breaking digging, no pesticides, no problems with groundhogs or deer or rabbits or squirrels, no watering worries, no drought regulations to follow, no insects and insect repellent, no over-sized zuccini. You can still plant other things if that's your desire. I started out with one rusted bicycle wheel years ago, surrounded it with lovely flowers, which were promptly eaten by wildlife. The circle of life.
So on the up side and in conclusion, you are getting outdoor exercise. You are cleaning up your little part of the planet we currently call home. And in this time of hustle and what's next on the neverending-to-do list, this is my version of creating something that serves no purpose, can be reconfigured, doesn't need electricity or gas, and eventually returns to where it came. And if your neighbors with their garden gnomes and topiaries gripe, talk to them about something else to ease their troubled minds. Or you can say with pride, this is my rust garden.