Preparing a hellstrip for planting
We have a large 10x50 hellstrip (aka parking strip) that is currently a mix of grass and many weeds. We would like to plant a pollinator garden of resilient native species. Our dirt is very clay like and dense. I’ve ordered a bunch of bareroot plants to arrive end of feb or early March. Im wondering in the intervening months how to best prepare our soil and remove the grass. I’ve heard a number of techniques but am not sure which is best. Our neighbor just laid out cardboard over her grass over the winter to kill it then threw compost on top. I’m just worried this won’t loosen then underlying clay for roots to thrive. I’ve heard tilling this time of year is actually bad for future plant roots but would be a good way to loosen the soil and I could add compost to build nutrients. What would you suggest?
Multnomah County Oregon
Thank you for your question. Had you asked this a couple of months ago, you would have had time to apply both the cardboard to kill the grass, and adding organic matter to help with soil compaction. You are correct in that tilling destroys the soil structure, and is not recommended. A sod remover may still be a method to take off the top of the grass, but will probably leave underground rhizomes. You can also use a spading fork, which will allow some grass removal and promote aeration. The problem with putting down cardboard and then covering it with compost is that the cardboard blocks the valuable soil microbes from reaching the organic materials and, to some extent, also prevent water from reaching them and, therefore, the roots. I'd suggest you use a hand tool to remove as much of the grass and rhizomes as possible, and then add organic matter as suggested by this OSU Extension article: Improving Garden Soils with Organic Matter | OSU Extension Catalog | Oregon State University
I hope this is helpful. Good luck!