Growing roses in clay soil can be a challenge because the fine particles in clay soil compact to form a very hard layer that makes the clay almost impenetrable. Without proper drainage, your rose roots will sit in water collecting on the layer of clay and begin to rot. Roses thrive in soil that's known as loam--a nutrient-rich, powdery soil that drains well. If you're dealing with clay soil, amendments can be made to improve the drainage to grow beautiful roses.
Cut straight down into the soil, away from decaying organic matter such as leaves or dead plants if possible, with your hand trowel to obtain a 3-inch cutting of soil from the area where you wish to plant your roses. Place the sample in a clean, plastic container. If you're planting more than one plant, you may wish to obtain samples from each section of the garden and mix them in your plastic container for a more accurate sample of the whole garden.
Take the soil sample to your local cooperative extension office or a full-service garden center for testing. Often the test is free, but it might cost a few dollars. The test will tell the soil's makeup, its pH level, and suggestions on how to amend it for a more balanced consistency. Be sure to mention that you are growing roses, so they can offer any tips for creating a loamy soil right for your growing zone. Purchase the suggested amendments, such as compost, peat moss or sand, among other possibilities. With clay soil, the trick is to add as much organic matter as possible to break up those fine clay particles and keep them loose.
Turn amendments, one at a time, into the garden at least 18 inches deep with a spade. Continue to turn the soil over, adding more amendments as needed until a powdery consistency is achieved.
Dig a hole at least 16 inches deep and fill it with water to test the drainage. If water sits in the hole, continue to add more organic matter such as compost, dried leaves or seaweed. Dig a second hole in another spot to test drainage again.
Add bone meal and turn it in to the soil. Bone meal is a vital component to healthy roses, made up of ground cow bones, that adds a high level of calcium to the soil. Bone meal is available in garden centers and can be found in rose food, fertilizer specially made for roses.
Plant your rose as instructed on the packaging. Planting instructions are different for potted roses than for bare-root plants. Potted roses may have compostable packaging that just requires planting the whole box in a hole twice its size, while bare-root plants require more specific instructions--typically you create a mound inside the hole and place roots in specific areas for planting.