Q: I needed to transplant plant some azaleas to a spot where Bermuda grass was growing. I went to a garden center and purchased a product that promised to kill all weeds. The active ingredient was prometon. A friend says the stuff will stay in the ground, killing plants, for years. What do you say?
A: I say you should have taken your friend with you to the garden center. Prometon is a soil sterilant, killing everything that attempts to grow where it has been applied. It remains in the soil for six months to three years, depending on weather. If you had read the label in its entirety, you would have noticed the line “Bare ground weed and grass killer. Do not apply to lawn areas or desirable vegetation.”
The normal use of Prometon is around storage tanks, fences and gravel parking lots. It gradually disappears as it is exposed to sunlight, rainfall and soil organisms. If you want to have anything more than pine straw in the spot where it was applied, your best choice is to remove all of the soil to a depth of four inches and replace it with fresh topsoil. If that is too much work, rototill the spot a few times in the next six months to maximize the decomposition. Next May, scatter some rye or fescue grass seed onto the area. If the chemical is gone, the seeds will sprout. If the seeds don’t germinate, wait another month and try planting grass once more. When the grass sprouts vigorously, you’ll know that you can plant in the bare area again.
Another idea, suggested by a friend, is to plant the azaleas in individual whiskey barrels filled with potting soil. As long as the plant roots don’t touch the soil, your azaleas will be fine. In a year or two they can be moved to their original destination.