Plants for ditch
I have a 10 foot deep ditch on my property, with a very steep bank. Right now the slope has thistle and other weeds, an in some places very little. I'd like to ensure there's no erosion, but the thistles and other weeds keep encroaching on the lawn. I'm looking for recommended plants to stabilize the slopes yet eliminate the thistle and other weeds.
Delaware County Ohio
Thanks for using Ask a Master Gardener with your question. A 10' deep ditch can certainly be a challenge.
I have found a few lists that may help you with plant selection to help prevent erosion. You stated that the slope is steep, so it may be a challenge to get new plant established. Some sites suggested using a geo-textile to stabilize the slope and planting through that material. Having some experience with the material, I think that has the potential to create more issues for you since you are also dealing with thistles.
Dealing with the thistles, there are no plants or planting technique that will allow you to have plants out compete the thistle infestation. You will need to eliminate them and other weeds before you try to plant. I know of no plants that will out compete weed infestations.
Native grasses seem to be the best choice, but there are several native sedges as well, that would be a more refined look verses the grasses, which are larger growing. As well, there are some shrubs that will spread by sucker growth, making them good for erosion control. You would need to control weeds until they have a chance to become fully established.
Here are the lists of planting that I have located to use on the slope. There are some native plant nurseries in your county that may carry some of these suggestions.
Here is a list I found from Cornell that includes not only native, but other choices for erosion control plantings:
In addition, here is information about control of thistles:
Hope this gives you some direction. I believe using native plants in your project would be most successful. Thanks for your question.