That's just kind of the way this variety grows :-) It is described by various sources as "low, sprawling clump", "slowly creeping", "flower clusters are so heavy that they weigh down the supporting stems", etc.

Suggestions to manage this including cutting back to 12" each season (IME, that tends to make the stems less rigid) or using a tomato cage or other support system to hold the plant upright. FWIW, this only gets be about half the height of a typical arborescens.

oh dear! the flowers aren't so pretty all covered by dirt and other plants. thanks for the info, gardengal48, and for the info about the oakleaf. i will so enjoy getting more flowers. but getting any is a bonus for me in quebec.