TheGardenLady received this question from Pat:
I am getting ready to plant Knockout Roses in my garden in northern South Carolina, and wonder how to best prepare the soil? We have very dense red clay mixed with some sand. Any recommendations on how to get these roses off to their best start in this type of soil?
Sorry it took so long to get back to you with a response, but TheGardenLady went right to one the sources of KnockOut Roses (see here) to get you the answer. I added a link to Permatill, a product mentioned in this column.
Here is the advice from a spokesperson for Novalis Plants that Work:
Many roses prefer well-drained soil, so the hard wet clay soil that you have in zone 7b will require a few steps to turn it into the optimum growing medium for these beautiful floriferous hardy shrub roses. It is quite possible the Pink Double Knock Out rose (an exclusive Knock Out rose from Novalis Plants that Work) will do well even in your current soil type as it is a robust grower. However, amending your soil can certainly help.
Adding a soil conditioner which consists of a primary ingredient of expanded slate will add needed oxygen and drainage to the existing clay soil, Permatill or other similar brands. Till-up the top 8″-10″ of existing soil and spread a 2″ layer of Permatill across the surface area. The Permatill particles act as a reservoir for air, moisture, and water soluble nutrients.
Adding a one-half inch layer of garden compost to the area will reinvigorate the old clay soil with new organic matter and will help the rose thrive. Though, one of the best features of this plant is that it usually does very well in less than perfect growing conditions. So, I think you will find it to be a wonderful plant for your landscape.
Don Eberly
Spokesperson for Novalis Plants that Work