Hi, Well my guess is it's the variety. Tournament of Roses is a grafted rose and unless you can provide them with a lot of winter protection they do have a tendency to get less vigorous with each succeeding year in the north. Frankly, I live in Iowa and I finally gave up growing grafted hybrid teas, grandifloras and floribundas and focus only on varieties grown on their own roots such as Knock Out, Flower Carpet, and Rugosas. Also, clay soil is not an ideal environment for roses. They really need to have a rich, organic soil so I would definitely add compost, rotted manure and even fresh soil to your garden.