Q: Planning for my old age arthritis, I am building some large flower garden beds from railroad ties stacked two tall so I can weed without getting on my bad knees. I have some excess “crusher run” rock from Hurricane Ivan repair and plan to fill the sixteen inch height roughly as one third rock, one third brown fill dirt and then the top third as top soil or planting mixture to hold canna lilies, iris and gladiola bulbs. I assume the creosote in the used railroad ties is not toxic to the flowers after years of exposure to the environment. Are those proportions reasonable or would you recommend more or less of this or that?
A: I think you are right “on track”. Railroad crossties are typically 8 x 7 inches. You’ve stacked yours on edge, making the garden bed 16 inches deep. The bed looks to be 30 inches wide, perfect for reaching in from either side. The ties make a solid wall so you can lean on it when you get tired as you work.
The “one third – one third – one third” filling proportions sound right. The root zone will be deep enough to contain the roots of anything you might plant and also to hold enough moisture for your plants. My judgement is that any leachable creosote is long gone.
Be sure to cover the initial rock layer with a layer of weed blocking fabric to keep soil from sifting down around the stones.
I’m confident you’ll be gardening for many years to come!