Hi Steve,
We use the naturally arid environment of the province of Alberta to control our fleas. Hopefully others will weigh in on products they find work but are 'holistic'.
When in Oregon I did use the borate powders for good environmental control and was happy. For desparate cases, I would use the occasional dose of Advantage to institute control. Otherwise, my main thrust was to treat the patient. By de-inflamming the skin, it seemed to me I was removing easy access to a blood meal for the fleas, and limiting the amount of food from which to lay eggs and support a population. The formulas that do that are often anti-inflammatory, like Si Miao San. So back in the day, in Oregon, it was a combination of these three methods I relied upon.
I really hope others weigh in here, though, and let you know what is definitely working for them.
All the best,
Steve