Have had this plant before and recommended it to clients. Rick Darke says leaves take on dark red by July and turn wholly wine colored by September. After we moved, purchased three at a local nursery in May of 2015 and had almost no red leaves last year -- they turned brown in the fall. Thought it might be a first year problem, but now in July of the second year, only about 1% of the leaves are red. They face south and get 8-10 hours of sun per day. Just up the road, about 12 plants facing north have about 50% red leaves right now. Contacted nursery about problem and they have no idea. Have searched on Internet and found no clues. Any ideas would be greatly appreciated!
Panicum Virgatum ‘Shenandoah’
Certified GKH Gardening Expert
You are not alone in reports of lack of color in your Switchgrass.
My research showed many gardeners, especially in the northern climates have similar complaints of Shanandoah not living up to the hype.
If color is what your looking for the variety, Ruby Ribbons is reported to preform better.