Potted Roses in Willamette valley winters
Hi! I lost several potted roses last winter. I think I rotted the roots, because it was so warm in didn’t think they would go dormant—and didn’t put them up against the house like I had done before. My question is...how do I ensure my potted roses go dormant in the Willamette valley. Live in North Albany, surrounded by oaks and protected from wind.
Benton County Oregon
Hello. I think I have a handle on your issue. Last year you did not put the roses near the house, and you ended up with some root rot. Very possibly two things happened.
1. Because the plants were not under the eaves of the house, they received much more moisture than normal which built up in the pots causing the root rot.
2. Depending on the size, type of rose, and length of time the roses have been in these pots they most likely need to be re-potted. Potting soils break down after a couple of years and need to be refreshed. As the materials break down, they compact, and the roots start to get suffocated. If not done every couple of years you end up with a pot full of roots with little potting material resulting in an unhealthy situation for your plants roots.
Roots need water AND air to remain healthy. This happens with any plant in a pot over a long period of time. Be sure to prune the roots back. Look for brown, black, and mushy roots, remove all of these. Gently tease out remaining roots from the compacted root mass and re-pot in fresh potting soil. A good way to do this is to use gently running water to soften and wash out old potting materials. Depending on the size of the root balls versus the size of the container they are planted in you may also want to replace the pots with larger ones. Ideally you don't want the root ball to be butted up against the sides or bottom of your container. You want soil all the way around and below. This provides roots insulation from extreme temperatures and gives your plant a healthy environment to grow into. Be sure that all new pots have ample drainage holes and that water runs freely through the pots when you are done. You should elevate the pots from the concrete or decking that they are sitting on to ensure proper air and water flow. This can be achieved with 'pot feet' which come in lots of forms, most commonly clay which once 3 or 4 are inserted around the pot raise the pot a couple inches off the surface they are sitting on to allow for airflow in and for water drainage out of the bottom of the pot. If you do put your plants up near the house as normal choose a south or west facing wall to take advantage of sunny days. Plants under house eaves may need to be watered occasionally during our winter months, especially when we are expecting a cold snap. Well-watered and moist roots are better able to survive cold windy weather.