I have some bare spots in my backyard due to the every enlarging Bradford pear trees creating a widening area of shade. Apparently Bermuda grass doesn't like shade. I've started planting fescue in some areas last year with moderate success. Trouble is, the problem areas are located along a drainage swale, so the seed I plant gets washed out...even with a light rainfall. How do I keep this stuff anchored long enough to take root? Or do I need to look for fescue sod?