I've a question about the panicles on pampas grass, when do they appear?

A motel two blocks away and myself both have the same soil and climate. We both got what was labeled as the same pampas grass from the same nursery at the same time. The plants get the same sunshine. The panicles on the grass at the motel appear about thee weeks to a month before mine do.

There are two differences. The motel has a professional landscaper who may fertilize and they have drip irrigation. I flood mine with water from the koi pond twice a week. Do you think either of these could make a three week difference in the appearance of the panicles?