To begin with, in hot California summers, many roses slow down on blooming.
This is natural. You can only do so much to force them, and it sounds like you've done more than you should.
In fact, immature roses should not be pushed with high level fertilizers OR hard pruning --
The poor dears need time to grow roots, before they can bloom long and heavily.

My best suggestion: Water your roses well and regularly.
Try giving them some alfalfa tea.
Otherwise, LEAVE THEM ALONE.
Let them recover at their own pace, and you will probably see bloom in the fall.

Jeri

I deadhead minimally, unless I have a monster grower like Lynn Anderson. I think they did a study somewhere and found that you get more blooms with just snapping the bloom off or cutting right below it. I think you are fretting too much. You should get blooms either way, but it will take longer with your type of severe pruning. I just expect leggy roses by the end of the summer. I want flowers, not perfect bushes.
Once your roses are established and you are deadheading blooms, you should have flowers all the time. Most of my roses are never without blooms.
Have fun experimenting.
Kathy

I think the advice you quoted is exaggerated. If you cut below the previous cut, the new growth might be delayed for an additional week because there are fewer growth hormones in the lower canes. But it would not cause dormancy. However, normally we don't cut below the previous cut. The growth of plants is fueled only by leaves in sunlight, so taking off a lot just weakens the plant.

For maximum growth and flowering, and on weak plants, just remove the flowers. For size control on plants growing vigorously, cut as low as two leaves above the previous cut. To make arching shrubs more upright and bushy, cut at or inside the top of the arch at an upward-facing bud site (leaf joint).

Just to pile it on.....only kidding, because a couple of us have already made this mistake and we feel your pain.....we've learned that the California Mediterranean climate produces different growth and therefore calls for different pruning than Jolly Old England. In NorCal, our spring flush is a full month sooner, meaning our blooming season is probably three months longer than southern England's. My part of Marin County is on a latitude of Sicily. It rains there all spring and summer and fall. It doesn't rain here at all most of of the spring, all summer and fall. Our roses need their foliage to shade the canes. We have no idea how intense our sun is, but I can attest to the fact that some of my best performing roses are blooming under shade cloth.

And one last thing. If you planted "English Roses," that's another problem. They may have great marketing, but for the California climate, there are far better producers out there, the kind that are never without bloom. They are evergreen and expect to have their leaves year round or close to it.