So I've arrived at a shocking conclusion in my Grand Unified Flower Theory, operating on a sample size of one (my town): flowers need water and sun!
Here are the data points:
1. It's been cloudy and raining a lot lately. Sucks. Seems to suck for hybridization, too. I get a random spawn here or there but they're not necessarily any good. I was doing a lot better when it was sunnier out and I would go around watering most flowers.
2. Because it's been rainy, nothing's been wilting. So I've been trying to water the pairs I want to spawn (e.g. orange/purple roses.) But they just stupidly sit there, not making sweet flower love.
3. On the day of the solstice, bright clear skies all day long, no rain. Nothing had wilted because it rained the day before. So I watered just the orange/purple rose pairs, since they're my current focus, and moved on. Next morning, tons of wilting, but four red+ roses!
4. It's been raining again. All flowers were watered yesterday despite the rain, and this morning, wilting is nonexistent but hybridization is looking crappy again*. One more red+ rose and nothing else special.
The one data point I don't have is whether rain counts exactly the same as hand-watering or not. I haven't wanted to risk losing a wilted flower to rain. It did work in past games, but I'm feeling awfully protective.
So. Does this jive with others' flower experiences?
* My town is so full of flowers now and they don't really have a pattern that makes it easy to spot new hybrids very well that I'm not 100% sure this was all I had, but I'm pretty sure.