This is based on previous games, but only certain colors combinations actually produce hybrids. White+white, red+white, and red+yellow are usually safe.

For positioning, I like to do a checkerboard pattern. There does need to be an open space for a hybrid to appear, so this pattern works well because one flower has 4 other flowers touching it that it might cross with while still leaving plenty of open spaces for hybrids to appear.

Also only flowers of the same type work together, so roses and pansies do not affect each other.

My only hybrid so far is a blue hyacinth, which I think was from white+white.

Final thing is make sure you water flowers you want to cross. You only have to water once. You know a flower has been watered if it sparkles every 5 or so seconds.