I have heard that if you want your bulbs to return as well every year, that they should be lifted and dried then stored in a cool spot for the summer like a garage.
I just wondered if you lifted yours or do you let them dry and plant over top of the yellowing foliage? I have trouble getting my tulips to rebloom. Last year I even fed them bone meal and don't see many coming back that will bloom. I am only seeing one leaf. I am in zone 6, Cincinnati. Bulbs definitely require Excedrin for me. I love them but they don't like me.
Your bed was beautiful by the way and I loved the "soldier" look.
I don't lift the bulbs here, although I know some people that do. I guess I'm just too lazy. This year I'm trying drought-tolerant annuals planted after the tulip foliage is done. The bulbs don't like being watered in summer.
I'm of the opinion that most of the non-species tulips.. the large showy ones.. cannot be expected to flower for more than several years. They go slowly downhill, and they never re-gain their blooming strength. To me, digging and replanting doesn't help.. bonemeal doesn't help.. the only small help is deadheading the spent flowers and refraining from removing the shabby foliage till the leaves are mostly yellow. If you get a good buy on tulips.. 50-cents or less.. and they only bloom for 3 years.. just replant them regularly and be happy with a relatively inexpensive show.