I have been breeding without fertilizer and the gold can myself in my my new town, and I average 3 hybrids a day. Here are some tricks to doing it:
1. Spread lots of pairs (like, 20 pairs or more) all across your town's mainland - not just the beach. Without fertilizer, the spots hybrids will spawn will be quite random, and only choosing a few pairs in visual distance won't work well.
2. Jacob's Ladder, Perfect town status, and the Gold Can to help spawn hybrids are total urban legends. There is
no tested evidence that they increase the chance of getting hybrids. You can get them without these attributes.
3 If you manage to get fertilizer, swarm a bunch of same-colored flowers all around the fertilizer, Kind of like this:
If you need to use two different colors, put them in a checkerboard around the fertilizer, like this:
Either way, this only works if you have fertilizer with you.
4. Certain hybrids like Pinks are unstable at first. The best way to do those is to keep trying to breed new Pinks from older ones, and separate and replace new Pinks from the old to breed with each other. Keep repeating this, and you will get Pinks that are much more stable.
Hopefully this advice helps you.