Fertilizing Blue Oat Grass…when And With What?
When should I fertilize the Blue Avena grasses in my landscape, and with what?
Certified GKH Gardening Expert
What you use will be, completely, up to you! They are not picky grasses, and will tolerate a wide range of foods, as long as they are all-purpose, or balanced (The NPK ratios will be best equal to each other, like 10-10-10) the fertilizer will not be too important. They aren't heavy feeders, and will tolerate a wide range of soils. You could consider a yearly top dressing of compost, as well.
Here is an article that will help you with the care of the grass: https://www.gardeningknowhow.com/ornamental/foliage/blue-oat-grass/ornamental-oat-grass.htm